There's a field whose initialization procedure differs enough
from the comment describing it that it's worth clarifying.

Signed-off-by: Martí Bolívar <marti.bolivar@nordicsemi.no>

The filename attribute no longer exists. Instead, we have a better
str() result for a ManifestImportFailed. Use it instead.

Signed-off-by: Martí Bolívar <marti.bolivar@nordicsemi.no>

Fixing the test case logic causes it to fail, so mark it xfail.
This is bug zephyrproject-rtos#663.

The test case test_group_filter_self_import() is incorrect, which
conveniently enough provides steps to reproduce.

The test case should read as follows (patch applies to f6f5cf6):

diff --git a/tests/test_manifest.py b/tests/test_manifest.py
index 14f2941..e934b71 100644
--- a/tests/test_manifest.py
+++ b/tests/test_manifest.py
@@ -2828,7 +2828,7 @@ def test_group_filter_imports(manifest_repo):
     sha2 = setup_project('project2', '[+gy,+gy,-gz]')

     v0_9_expected = ['+ga', '-gc']
-    v0_10_expected = ['-ga', '-gb', '-gc', '-gw', '-gy', '-gz']
+    v0_10_expected = ['-ga', '-gb', '-gc', '-gw', '-gz']

     #
     # Basic tests of the above setup.

In other words, west incorrectly concludes that group 'gy' is disabled
in this scenario, when it should be enabled.

The test creates the following layout, where ./mp/west.yml is the main
manifest:

    ───────────────────────────────────────
     File: ./mp/west.yml
    ───────────────────────────────────────
     manifest:
       version: "0.10"

       group-filter: [+ga,-gc]

       projects:
         - name: project1
           revision: ...
           import: true
         - name: project2
           revision: ...
           import: true

       self:
         import: self-import.yml
    ..
    ───────────────────────────────────────

    ───────────────────────────────────────
     File: ./project1/west.yml
    ───────────────────────────────────────
     manifest:
       group-filter: [-gw,-gw,+gx,-gy]
    ───────────────────────────────────────

    ───────────────────────────────────────
     File: ./project2/west.yml
    ───────────────────────────────────────
     manifest:
       group-filter: [+gy,+gy,-gz]
    ───────────────────────────────────────

    ───────────────────────────────────────
     File: ./mp/self-import.yml
    ───────────────────────────────────────
     manifest:
       group-filter: [-ga,-gb]
    ───────────────────────────────────────

The west docs say:

  In other words, let:

  - the submanifest resolved from self-import have group filter self-filter
  - the top-level manifest file have group filter top-filter
  - the submanifests resolved from import-1 through import-N have
    group filters filter-1 through filter-N respectively

  The final resolved group-filter value is then filter1 + filter-2 +
  ... + filter-N + top-filter + self-filter, where + here refers to
  list concatenation.

  - https://docs.zephyrproject.org/latest/develop/west/manifest.html

Applying these rules, the final filter should be concatenated from
./project1/west.yml, ./project2/west.yml, ./mp/west.yml,
./mp/self-import.yml, in that order. Since neither ./mp/west.yml nor
./mp/self-import.yml have a group filter which affects gy, the result
should be that it is enabled, since ./project2/west.yml enables it
explicitly.

Fix the test so it matches the expected behavior. We'll fix the
implementation in a separate commit.

Signed-off-by: Martí Bolívar <marti.bolivar@nordicsemi.no>

This is a more convenient way to construct manifests, so we might as
well have it around and use it to save some typing.

Signed-off-by: Martí Bolívar <marti.bolivar@nordicsemi.no>

This involves a rework of the group filter mechanism, which has the
side effect of fixing its behavior to match its documentation. We can
therefore drop the xfail on a related test.

This is a top level manifest key that takes a boolean. The default
value is 'true' and is west's current behavior. The behavior when
this value is false can be shown by this example:

  manifest:
    group-filter: [-foo]
    import-group-filters: false
    projects:
      - name: proj
        import: true
    self:
      import: submanifest.yml

Here, the final Manifest.group_filter attribute for the manifest
whose data are shown above will always be [-foo], regardless of what
whe imported manifest data from 'proj' or 'submanifest.yml' are.

The purpose of this extension is to allow the combination of 'groups'
and 'import':

- In previous versions of west, we could not combine the two, because
  in pathological edge cases, we could end up resolving an import for a
  group which was later disabled by an import that happened later on.

- With this new backwards-compatible enhancement to the manifest file
  format, we can combine 'import:' with 'groups:' in a single project
  whenever 'import-group-filters:' is 'false'. This is because we will
  know the final 'group_filter' attribute for the entire Manifest at
  the time we perform the import, and it cannot be changed later by
  any imports we might perform.

Since this new behavior would break backwards compatibility if made the
default, we make it explicitly opt-in by requiring
'import-group-filters: false'.

Fixes: zephyrproject-rtos#663
Fixes: zephyrproject-rtos#652

Signed-off-by: Martí Bolívar <marti.bolivar@nordicsemi.no>

Add initial coverage for "import-group-filters: false" as well
as some other related improvements.

Signed-off-by: Martí Bolívar <marti.bolivar@nordicsemi.no>

Improve error handling to avoid dumping stack.

Signed-off-by: Martí Bolívar <marti.bolivar@nordicsemi.no>