BLT 12 overwrites drush site alias default.site.yml

[benjifisher]

Describe the bug

When I add a multisite with blt recipes:multisite:init, BLT creates a Drush site alias for the new multisite, as expected, but also munges the default site alias.

To Reproduce
Steps to reproduce the behavior, ideally starting from a fresh install of BLT:

1. Make sure that drush/sites/default.site.yml has a valid URI (such as uri: https://default.lndo.site).
2. Run blt recipes:multisite:init --site-dir=newsite --site-uri=https://newsite.lndo.site --remote-alias=newsite.remote and accept the defaults.
3. Note that (1) has changed. The file now has uri: default.

Expected behavior

I expect that the site alias file newsite.site.yml is created, along with docroot/sites/newsite/, but that default.site.yml is unchanged.

BLT doctor output

+---------------------------+-------------------------------------+
| Property | Value |
+---------------------------+-------------------------------------+
| %paths.%root | /app/docroot |
| %paths.%site | sites/default |
| %paths.%modules | sites/all/modules |
| %paths.%themes | sites/all/themes |
| %paths.%config-sync | /app/config/default |
| %paths.%files | sites/default/files |
| %paths.%temp | /tmp |
| %paths.%private | /app/files-private/default |
| admin-theme | seven |
| alias-searchpaths.0 | /app/drush/sites |
| blt-version | 12.2.0 |
| bootstrap | Successful |
| composer-version | Composer 1.10.9 2020-07-16 12:57:00 |
| config-sync | /app/config/default |
| db-driver | mysql |
| db-hostname | database |
| db-name | drupal9 |
| db-password | drupal9 |
| db-port | 3306 |
| db-status | Connected |
| db-username | drupal9 |
| drupal-settings-file | sites/default/settings.php |
| drupal-version | 9.0.2 |
| drush-alias-files.0 | /app/drush/sites/default.site.yml |
| drush-alias-files.1 | /app/drush/sites/multi1.site.yml |
| drush-cache-directory | /var/www/.drush/cache |
| drush-conf.0 | /app/vendor/drush/drush/drush.yml |
| drush-conf.1 | /app/drush/drush.yml |
| drush-script | /app/vendor/drush/drush/drush |
| drush-temp | /tmp |
| drush-version | 10.3.1 |
| files | sites/default/files |
| install-profile | tufts |
| modules | sites/all/modules |
| php-bin | /usr/local/bin/php |
| php-conf.1 | false |
| php-os | Linux |
| private | /app/files-private/default |
| root | /app/docroot |
| site | sites/default |
| stacks.drupal-vm.inited | false |
| stacks.dev-desktop.inited | false |
| temp | /tmp |
| theme | tuftstheme |
| themes | sites/all/themes |
| uri | http://default |
+---------------------------+-------------------------------------+
+--------------------------------------+--------------------+
| Check | Problem |
+--------------------------------------+--------------------+
| NodeCheck:checkNodeVersionFileExists | .nvmrc file exists |
+--------------------------------------+--------------------+

System information

• Operating system type: Linux
• Operating system version: Ubunto 20.04
• BLT version: 12.2.0

Additional context
Add any other context about the problem here.

[danepowell]

I'm not sure why the multisite command should touch the default site at all, seems like either it should leave the file alone if it exists already, or we should remove this logic for the default site altogether.

[benjifisher]

I vote for "remove this logic for the default site altogether".

I am not sure when the default site gets set up. I think it happened the first time I ran blt setup. If not, or if I need to update the default site alias, I can always use blt recipes:multisite:init --site-dir=default.

[danepowell]

@benjifisher do you want to help test a fix? #4297