vendor/composer/composer/src/Composer/installed.php: failed to open stream 2.1.0

[pookmish]

My composer.json:

{
    "name": "su-hsdo/suhumsci",
    "description": "Project template for Drupal 9 projects with a relocated document root",
    "type": "project",
    "license": "GPL-2.0-or-later",
    "homepage": "https://github.com/SU-HSDO/suhumsci",
    "repositories": [
        {
            "type": "composer",
            "url": "https://packages.drupal.org/8"
        },
        {
            "url": "https://git.drupalcode.org/issue/domain_301_redirect-2954889",
            "type": "vcs"
        },
        {
            "url": "https://git.drupalcode.org/issue/audio_embed_field-3146159",
            "type": "vcs"
        },
        {
            "type": "package",
            "package": {
                "name": "kenwheeler/slick",
                "version": "1.8.0",
                "type": "drupal-library",
                "dist": {
                    "url": "https://github.com/kenwheeler/slick/archive/1.8.0.zip",
                    "type": "zip"
                },
                "require": {
                    "composer/installers": "^1.2.0"
                }
            }
        },
        {
            "type": "package",
            "package": {
                "name": "dinbror/blazy",
                "version": "1.8.2",
                "type": "drupal-library",
                "dist": {
                    "url": "https://github.com/dinbror/blazy/archive/1.8.2.zip",
                    "type": "zip"
                },
                "require": {
                    "composer/installers": "^1.2.0"
                }
            }
        },
        {
            "type": "package",
            "package": {
                "name": "ckeditor-plugin/a11ychecker",
                "version": "1.1.1",
                "type": "drupal-library",
                "dist": {
                    "url": "https://download.ckeditor.com/a11ychecker/releases/a11ychecker_1.1.1.zip",
                    "type": "zip"
                },
                "require": {
                    "composer/installers": "~1.0"
                }
            }
        },
        {
            "type": "package",
            "package": {
                "name": "ckeditor-plugin/balloonpanel",
                "version": "4.14.0",
                "type": "drupal-library",
                "dist": {
                    "url": "https://download.ckeditor.com/balloonpanel/releases/balloonpanel_4.14.0.zip",
                    "type": "zip"
                },
                "require": {
                    "composer/installers": "~1.0"
                }
            }
        },
        {
            "type": "package",
            "package": {
                "name": "ckeditor-plugin/link",
                "version": "4.14.0",
                "type": "drupal-library",
                "dist": {
                    "url": "https://download.ckeditor.com/link/releases/link_4.14.0.zip",
                    "type": "zip"
                },
                "require": {
                    "composer/installers": "~1.0"
                }
            }
        },
        {
            "type": "package",
            "package": {
                "name": "ckeditor-plugin/fakeobjects",
                "version": "4.14.0",
                "type": "drupal-library",
                "dist": {
                    "url": "https://download.ckeditor.com/fakeobjects/releases/fakeobjects_4.14.0.zip",
                    "type": "zip"
                },
                "require": {
                    "composer/installers": "~1.0"
                }
            }
        },
        {
            "type": "package",
            "package": {
                "name": "ckeditor-plugin/liststyle",
                "version": "4.14.0",
                "type": "drupal-library",
                "dist": {
                    "url": "https://download.ckeditor.com/liststyle/releases/liststyle_4.14.0.zip",
                    "type": "zip"
                },
                "require": {
                    "composer/installers": "~1.0"
                }
            }
        }
    ],
    "require": {
        "acquia/blt": "^12.0",
        "acquia/blt-simplesamlphp": "dev-master",
        "ckeditor-plugin/liststyle": "4.14.0",
        "composer/installers": "^1.9",
        "cweagans/composer-patches": "^1.7",
        "dinbror/blazy": "^1.8",
        "drupal/acquia_connector": "^3.0",
        "drupal/acquia_purge": "^1.1",
        "drupal/address": "^1.9",
        "drupal/addtocal": "^2.0",
        "drupal/admin_login_path": "^2.0",
        "drupal/admin_toolbar": "^3.0",
        "drupal/allowed_formats": "^1.3",
        "drupal/anchor_link": "^2.4",
        "drupal/asset_injector": "^2.7",
        "drupal/audio_embed_field": "dev-3146159-d9-ready",
        "drupal/auto_entitylabel": "^3.0@beta",
        "drupal/better_normalizers": "^1.0@beta",
        "drupal/block_class": "^1.3",
        "drupal/block_content_permissions": "^1.10",
        "drupal/block_field": "^1.0@RC",
        "drupal/bricks": "^2.0",
        "drupal/cancel_button": "^1.1",
        "drupal/chosen": "^3.0",
        "drupal/ckeditor_liststyle": "^1.4",
        "drupal/color_field": "^2.4",
        "drupal/colorbox": "^1.7",
        "drupal/components": "^2.0",
        "drupal/conditional_fields": "^1.0@alpha",
        "drupal/config_filter": "^1.0",
        "drupal/config_ignore": "^2.2",
        "drupal/config_pages_overrides": "^1.0@beta",
        "drupal/config_readonly": "^1.0@beta",
        "drupal/config_split": "^1.0",
        "drupal/config_update": "^1.7",
        "drupal/confirm_leave": "^1.0@beta",
        "drupal/content_access": "^1.0@alpha",
        "drupal/core-composer-scaffold": "^9",
        "drupal/core-project-message": "^9",
        "drupal/core-recommended": "~9.1.0",
        "drupal/default_content": "^2.0",
        "drupal/diff": "^1.0",
        "drupal/domain_301_redirect": "dev-2954889-d9-ready",
        "drupal/draggableviews": "^2.0",
        "drupal/ds": "^3.9",
        "drupal/eck": "^1.0@beta",
        "drupal/editor_advanced_link": "^1.8",
        "drupal/embed": "^1.4",
        "drupal/encrypt": "^3.0",
        "drupal/entity_embed": "^1.1",
        "drupal/entity_reference_exposed_filters": "^1.0@alpha",
        "drupal/entity_reference_revisions": "^1.3",
        "drupal/entityqueue": "^1.2",
        "drupal/environment_indicator": "^4.0",
        "drupal/extlink": "^1.5",
        "drupal/fakeobjects": "^1.1",
        "drupal/field_formatter_class": "^1.4",
        "drupal/field_group": "^3.1",
        "drupal/field_permissions": "^1.1",
        "drupal/fontawesome": "^2.17",
        "drupal/google_analytics": "^3.1",
        "drupal/honeypot": "^2.0",
        "drupal/imagemagick": "^3.1",
        "drupal/insert": "^2.0",
        "drupal/key": "^1.14",
        "drupal/layout_builder_component_attributes": "^1.1",
        "drupal/layout_builder_modal": "^1.1",
        "drupal/layout_paragraphs": "^1.0@beta",
        "drupal/masquerade": "^2.0@beta",
        "drupal/maxlength": "^1.0@RC",
        "drupal/menu_admin_per_menu": "^1.3",
        "drupal/menu_block": "dev-1.x",
        "drupal/menu_link_weight": "^1.0@beta",
        "drupal/menu_position": "^1.0@beta",
        "drupal/metatag": "^1.14",
        "drupal/migrate_source_csv": "^3.4",
        "drupal/mysql56": "^1.1",
        "drupal/node_revision_delete": "^1.0@RC",
        "drupal/paragraphs_edit": "^2.0@alpha",
        "drupal/path_redirect_import": "^1.0@beta",
        "drupal/pathauto": "^1.8",
        "drupal/porterstemmer": "^1.1",
        "drupal/printfriendly": "^3.5",
        "drupal/publishcontent": "^1.2",
        "drupal/rabbit_hole": "^1.0-beta4",
        "drupal/real_aes": "^2.3",
        "drupal/redirect": "^1.6",
        "drupal/role_delegation": "^1.1",
        "drupal/search_api": "^1.18",
        "drupal/seckit": "^2.0",
        "drupal/shield": "^1.4",
        "drupal/shortcut_menu": "^2.0",
        "drupal/slick_paragraphs": "^2.0",
        "drupal/smart_date": "^3.1",
        "drupal/smart_trim": "^1.3",
        "drupal/stage_file_proxy": "^1.1",
        "drupal/taxonomy_menu_ui": "^1.4",
        "drupal/term_condition": "^2.0",
        "drupal/ui_patterns": "^1.2",
        "drupal/ui_patterns_field_variants": "1.x-dev",
        "drupal/video_embed_field": "^2.4",
        "drupal/view_unpublished": "^1.0",
        "drupal/viewfield": "^3.0@beta",
        "drupal/views_block_filter_block": "^1.0",
        "drupal/views_bulk_edit": "^2.4",
        "drupal/views_bulk_operations": "^3.9",
        "drupal/views_data_export": "^1.0",
        "drupal/views_ical": "^1.0@alpha",
        "drupal/views_infinite_scroll": "^1.7",
        "drupal/views_taxonomy_term_name_depth": "^7.0",
        "drupal/webform": "^6.0",
        "drupal/xmlsitemap": "^1.0",
        "drupal/yearonly": "^9.0",
        "drush/drush": "^10.3",
        "harvesthq/chosen": "^1.8",
        "kenwheeler/slick": "^1.8",
        "onlyextart/colorbox": "dev-master#e58476becbc89dc671093d1bcd9f99b2167fa8f7",
        "sainsburys/guzzle-oauth2-plugin": "^3.0",
        "spatie/calendar-links": "~1.5.0",
        "su-sws/nobots": "^8.2",
        "su-sws/react_paragraphs": "^8.2",
        "su-sws/stanford_basic": "dev-8.x-2.x#9d6391431de1aefa93c4dfe671e309cef1496d81",
        "su-sws/stanford_fields": "^8.1",
        "su-sws/stanford_media": "^8.2",
        "su-sws/stanford_migrate": "^8.1",
        "su-sws/stanford_ssp": "^8.1",
        "su-sws/stanford_text_editor": "^8.1"
    },
    "require-dev": {
        "acquia/blt-drupal-test": "^1.0",
        "phpspec/prophecy-phpunit": "^2.0",
        "raveren/kint": "^3.1",
        "su-sws/blt-sws": "dev-main",
        "su-sws/drupal-dev": "^8.2"
    },
    "conflict": {
        "drupal/drupal": "*"
    },
    "minimum-stability": "dev",
    "prefer-stable": true,
    "config": {
        "sort-packages": true,
        "discard-changes": true
    },
    "scripts": {
        "post-drupal-scaffold-cmd": [
            "patch -p1 < patches/htaccess.patch"
        ]
    },
    "extra": {
        "enable-patching": true,
        "patches": {
            "drupal/addtocal": {
                "https://www.drupal.org/project/addtocal/issues/3197306": "https://www.drupal.org/files/issues/2021-04-09/field-token-values-not-cleared-when-empty-3197306-2.patch",
                "https://www.drupal.org/project/addtocal/issues/3200494": "https://www.drupal.org/files/issues/2021-02-26/1551026-smart_date.patch"
            },
            "drupal/anchor_link": {
                "https://www.drupal.org/project/anchor_link/issues/2958532": "https://www.drupal.org/files/issues/2019-01-11/anchor_link-linkit-support_2958532.patch"
            },
            "drupal/bricks": {
                "https://www.drupal.org/project/bricks/issues/3003176": "https://www.drupal.org/files/issues/2018-09-28/bricks-entity_usage-3003176.patch"
            },
            "drupal/conditional_fields": {
                "https://www.drupal.org/project/conditional_fields/issues/3191984": "https://www.drupal.org/files/issues/2021-01-21/3191984-3-notice-trying-to-access-offset-on-value-of-type-null.patch"
            },
            "drupal/config_ignore": {
                "https://www.drupal.org/project/config_ignore/issues/2857247": "https://www.drupal.org/files/issues/2020-01-11/support-for-export-2857247-44.patch",
                "https://www.drupal.org/project/config_ignore/issues/2865419": "https://www.drupal.org/files/issues/2020-07-20/config_ignore-wildcard_force_import.patch"
            },
            "drupal/core": {
                "https://www.drupal.org/project/drupal/issues/2999491": "https://www.drupal.org/files/issues/2020-10-06/2999491--reusable-title-display--56.patch",
                "https://www.drupal.org/project/drupal/issues/2981837": "https://www.drupal.org/files/issues/2019-05-22/findMigrationDependencies-null-process-value-2981837-5.patch",
                "https://www.drupal.org/project/drupal/issues/2925297": "https://www.drupal.org/files/issues/2019-09-26/core-typed_config_handle_missing_config-2925297-18.patch",
                "https://www.drupal.org/project/drupal/issues/3020876": "https://www.drupal.org/files/issues/2020-09-25/contextual_links_with_LB-3020876-38.patch",
                "https://www.drupal.org/project/drupal/issues/1349080": "https://www.drupal.org/files/issues/2021-04-02/1349080-487.patch"
            },
            "drupal/domain_301_redirect": {
                "https://www.drupal.org/project/domain_301_redirect/issues/3010370": "https://www.drupal.org/files/issues/2019-09-24/domain_301_redirect-roles-3010370-3.patch"
            },
            "drupal/ds": {
                "https://www.drupal.org/project/ds/issues/2939322": "https://www.drupal.org/files/issues/2020-01-07/ds-content_entity-2939322-11.patch"
            },
            "drupal/fakeobjects": {
                "https://www.drupal.org/project/fakeobjects/issues/3002953": "https://www.drupal.org/files/issues/2020-06-22/fakeobjects-missing_plugin-3002953-5.patch"
            },
            "drupal/google_analytics": {
                "https://www.drupal.org/project/google_analytics/issues/3178179": "https://www.drupal.org/files/issues/2020-11-19/3178179-13.patch"
            },
            "drupal/key": {
                "https://www.drupal.org/project/key/issues/2980072": "patches/contrib/key-encrypt-2980072-4.patch"
            },
            "drupal/linkit": {
                "https://www.drupal.org/node/2423093 & https://www.drupal.org/project/linkit/issues/2712951#comment-13833751": "https://www.drupal.org/files/issues/2020-09-23/linkit-for-link-field-2712951-190.patch"
            },
            "drupal/menu_link_weight": {
                "https://www.drupal.org/project/menu_link_weight/issues/3152926": "https://www.drupal.org/files/issues/2020-06-18/warnings-in-php-7-4-3152926-2.patch",
                "https://www.drupal.org/project/menu_link_weight/issues/2995896": "https://www.drupal.org/files/issues/2018-08-29/2995896-menu-admin-per-menu-support-fixes.patch"
            },
            "drupal/menu_position": {
                "https://www.drupal.org/project/menu_position/issues/3110502": "https://www.drupal.org/files/issues/2020-07-29/drupal-menu_position-WSOD-when-menu-parent-no-longer-exists-3110502-26.patch",
                "https://www.drupal.org/project/menu_position/issues/3146668": "https://www.drupal.org/files/issues/2020-06-08/drupal9_schemaexception-3146668-2.patch"
            },
            "drupal/paragraphs": {
                "https://www.drupal.org/project/paragraphs/issues/2895561": "https://www.drupal.org/files/issues/2021-05-06/paragraphs-2895561-32.patch"
            },
            "drupal/path_redirect_import": {
                "https://www.drupal.org/project/path_redirect_import/issues/3153871": "https://www.drupal.org/files/issues/2020-06-22/path_redirect_import-d9-3153871-4.patch"
            },
            "drupal/redirect": {
                "https://www.drupal.org/project/redirect/issues/3057250": "https://www.drupal.org/files/issues/2020-12-14/validation-issue-3057250-29.patch"
            },
            "drupal/simplesamlphp_auth": {
                "https://www.drupal.org/project/simplesamlphp_auth/issues/2124117": "https://www.drupal.org/files/issues/2020-02-01/2124117-6-reroll-14.patch",
                "https://www.drupal.org/project/simplesamlphp_auth/issues/2936889": "https://www.drupal.org/files/issues/2020-07-31/simplesamlphp_auth-avoid_unexpected_redirect-2936889-12-d8.patch"
            },
            "drupal/ui_patterns": {
                "patches": "patches/contrib/ui_patterns_views-preview.patch",
                "https://github.com/nuvoleweb/ui_patterns/issues/304": "https://patch-diff.githubusercontent.com/raw/nuvoleweb/ui_patterns/pull/318.diff"
            },
            "drupal/video_embed_field": {
                "https://www.drupal.org/project/video_embed_field/issues/2913925": "https://www.drupal.org/files/issues/2018-07-09/retrieve-title-2913925-5.patch"
            },
            "drupal/views_taxonomy_term_name_depth": {
                "https://www.drupal.org/project/views_taxonomy_term_name_depth/issues/2877249": "https://www.drupal.org/files/issues/2020-05-01/2877249_21.patch"
            },
            "su-sws/stanford_basic": {
                "D9 Update": "patches/contrib/stanford_basic.patch"
            }
        },
        "drupal-scaffold": {
            "locations": {
                "web-root": "docroot/"
            }
        },
        "installer-paths": {
            "docroot/core": [
                "type:drupal-core"
            ],
            "docroot/libraries/{$name}": [
                "type:drupal-library"
            ],
            "docroot/modules/contrib/{$name}": [
                "type:drupal-module"
            ],
            "docroot/profiles/contrib/{$name}": [
                "type:drupal-profile"
            ],
            "docroot/themes/contrib/{$name}": [
                "type:drupal-theme"
            ],
            "drush/Commands/contrib/{$name}": [
                "type:drupal-drush"
            ],
            "docroot/modules/custom/{$name}": [
                "type:drupal-custom-module"
            ],
            "docroot/themes/custom/{$name}": [
                "type:drupal-custom-theme"
            ]
        },
        "custom-installer": {
            "docroot/modules/stanford/{$name}/": [
                "type:stanford-module"
            ],
            "docroot/themes/stanford/{$name}/": [
                "type:stanford-theme"
            ],
            "docroot/profiles/stanford/{$name}/": [
                "type:stanford-profile"
            ],
            "docroot/libraries/{$name}/": [
                "type:component",
                "ckeditor/ckeditor",
                "enyo/dropzone",
                "components/jquery",
                "harvesthq/chosen"
            ],
            "vendor/{$vendor}/{$name}/": [
                "type:library"
            ]
        }
    },
    "autoload": {
        "psr-4": {
            "Humsci\\": "blt/src/"
        }
    },
    "autoload-dev": {
        "psr-4": {
            "Drupal\\Tests\\hs_basic_page\\": "docroot/modules/humsci/hs_basic_page/tests",
            "Drupal\\Tests\\hs_bugherd\\": "docroot/modules/humsci/hs_bugherd/tests",
            "Drupal\\Tests\\hs_courses_importer\\": "docroot/modules/humsci/hs_courses/modules/hs_courses_importer/tests",
            "Drupal\\Tests\\hs_field_helpers\\": "docroot/modules/humsci/hs_field_helpers/tests",
            "Drupal\\Tests\\hs_table_filter\\": "docroot/modules/humsci/hs_table_filter/tests"
        }
    }
}

Output of composer diagnose:

Checking composer.json: WARNING
The package "onlyextart/colorbox" is pointing to a commit-ref, this is bad practice and can cause unforeseen issues.
The package "su-sws/stanford_basic" is pointing to a commit-ref, this is bad practice and can cause unforeseen issues.
require.acquia/blt-simplesamlphp : unbound version constraints (dev-master) should be avoided
require.ckeditor-plugin/liststyle : exact version constraints (4.14.0) should be avoided if the package follows semantic versioning
require.drupal/ui_patterns_field_variants : exact version constraints (1.x-dev) should be avoided if the package follows semantic versioning
require.onlyextart/colorbox : unbound version constraints (dev-master#e58476becbc89dc671093d1bcd9f99b2167fa8f7) should be avoided
Checking platform settings: OK
Checking git settings: OK
Checking http connectivity to packagist: OK
Checking https connectivity to packagist: OK
Checking github.com oauth access: OK
Checking disk free space: OK
Checking pubkeys: FAIL
Missing pubkey for tags verification
Missing pubkey for dev verification
Run composer self-update --update-keys to set them up
Checking composer version: You are not running the latest stable version, run `composer self-update` to update (1.10.19 => 2.1.0)
Composer version: 1.10.19
PHP version: 7.4.9
PHP binary path: /usr/bin/php7.4
OpenSSL version: OpenSSL 1.1.1f  31 Mar 2020

(note, I have to run my global composer as V1 due to some platform dependencies on the nested dependencies.)

When I run this command:

vendor/bin/blt -vvv

I get the following output:

PHP Warning:  require([path]/vendor/composer/composer/src/Composer/installed.php): failed to open stream: No such file or directory in [path]/vendor/composer/composer/src/Composer/InstalledVersions.php on line 319
PHP Fatal error:  require(): Failed opening required '[path]/vendor/composer/composer/src/Composer/installed.php' (include_path='[path]/vendor/pear/archive_tar:[path]/vendor/pear/console_getopt:[path]/vendor/pear/pear-core-minimal/src:[path]/vendor/pear/pear_exception:.:/usr/share/php') in [path]/vendor/composer/composer/src/Composer/InstalledVersions.php on line 319

And I expected this to happen:

BLT Unknown

Usage:
  command [options] [arguments]

Options:
  -h, --help                     Display this help message
  -q, --quiet                    Do not output any message
  -V, --version                  Display this application version
      --ansi                     Force ANSI output
      --no-ansi                  Disable ANSI output
  -n, --no-interaction           Do not ask any interactive question
  -D, --define=DEFINE            Define a configuration item value. (multiple values allowed)
      --environment=ENVIRONMENT  Set the environment to load config from blt/[env].yml file.
      --site=SITE                The multisite to execute this command against.
  -v|vv|vvv, --verbose           Increase the verbosity of messages: 1 for normal output, 2 for more verbose output and 3 for debug

Available commands:
  help                                 Displays help for a command
  ..........

Downgrading to 2.0.14 solved the issue and I believe the issues comes from this commit: 82cffa1

[Seldaek]

Ok yeah that is a tricky case where composer/composer is installed as a package in the vendor dir and it appears to be using the InstalledVersions.php class from the vendor/composer/composer/src/... dir and not the one copied from vendor/composer/InstalledVersions.php. So the relative require with __DIR__ does not work.

I unfortunately can't seem to reproduce the issue with your composer.json, so I wonder if there is some other factor at play causing this..

[Seldaek]

Can you perhaps look in vendor/composer/autoload_classmap.php search for InstalledVersions and copy the whole line here?

Also please try to install again after composer self-update --snapshot first to see if that by any chance perhaps fixes it already, as there was an autoload related regression I fixed.

[pookmish]

composer self-update --snapshot appears to have at least prevented the fatal error. It now produces a similar but different warning:
PHP Warning: include(): Failed opening '[path]/vendor/composer/../composer/InstalledVersions.php'

In the autoload_classmap.php file here's the line you requested: 'Composer\\InstalledVersions' => $vendorDir . '/composer/InstalledVersions.php',

[Seldaek]

Do you have a way to debug or manually look at what happens when you execute blt? If you could get me a stack trace for that include which fails it would be interesting. I don't understand why the path is looking wrong like that.

Do you run a single composer install or multiple in several paths? I.e. is there another autoload_classmap.php somewhere else?

Finally, if you find a way to build a minimal repro case with less packages and that you can ensure let's me reproduce the problem only with the composer. json in an empty directory that'd be great. Or if you can build a repro git repo if you need more files to trigger it that works too. Sorry I know these aren't all easy asks but if i can't repro I'm afraid this will be very hard to fix.

[pookmish]

Well it appears in my attempts to create a more simple composer.json, the problem has resolved itself.

I want to believe that running composer self-update --snapshot earlier was the primary solution, but it still required rebuilding the vendor directory after running (or at least vendor/composer). I did run composer dumpautoload after running the self-update, but that didn't resolve it at that time.

I checked the InstalledVersions in the autoload_classmap.php, and it still looks the same as when I had the error, so I'm leaning towards my conclusion i mentioned earlier.

Thanks for the help.

[pookmish]

I guess this is technically still a bug. I dug a little bit and i confirmed that composer self-update did indeed fix the issue. It was fixed because then my global composer was then at ^2.0. If i reset back to version 1 for the global composer composer self-update --1 and rebuilt the vendor directory. the fatal error returned.

Because some of my team members are still on composer v1 (other project dependencies and such) I'll re-open this and try to step through some parts.

[pookmish]

I did some data dumping, and it seems to come from this line. It seems something about the static method breaks with a global composer version 1.

It was pretty easy to fix this by adding a if (file_exists around line 319. Once I did that, the fatal error was gone.

[Seldaek]

Ok so I think what happens is because drupal/core-dev which you also require has a require on composer/composer (not entirely sure why), the InstalledVersions class is always present in the vendor dir regardless of Composer version. So when using composer 1 it doesn't load it from vendor/composer/InstalledVersions.php (which composer 2 would generate), but it autoloads it from vendor/composer/composer/src/Composer/InstalledVersions.php, which is there and technically the right class, but really not what blt expects to be loading. That class doesn't have the installed.php next to it so it fails.

I see a few options to fix this:

1. make sure that Composer\InstalledVersions is not autoloadable from composer/composer ever, and is only available as runtime if installed via composer 2
2. skip the include if the file hasn't been dumped to a vendor/composer/InstalledVersions.php during the install process.

I think I'd say maybe 1 but that might break composer (when developing it, not for users) in some edge cases.

@naderman any opinion here?

[Seldaek]

Ok went with option 2 for safety for now..