Add submodules: recursive temporarily, for testing

Add `submodules: recursive` to the `actions/checkout` step in every
workflow that runs the test suite (`cygwin-test.yml`,
`pythonpackage.yml`, `alpine-test.yml`). This is **temporary** and is
reverted after the next commit's bugfix, with the explicit intent of
demonstrating that the bugfix works regardless of which mechanism
populates the submodules.

The standing decision is to NOT use `submodules: recursive` in CI:
`init-tests-after-clone.sh` is the documented setup mechanism that
downstream packagers (Arch Linux and others) rely on, and keeping it as
the sole submodule source on upstream CI catches gitpython-developers#1713-class regressions
before they reach distros. See PR gitpython-developers#1715
(gitpython-developers#1715) for the
full rationale.

The CI run on this commit is expected to show:

- Cygwin (`test-cygwin`): the safe.directory bug still triggers, with
  the same `ValueError` / `IndexError` / `AssertionError` pattern as the
  previous commits. The bug is independent of which process clones the
  submodules; the gitdb worktree directory itself is created Admin-owned
  by the outer `git clone`'s checkout phase before any submodule init
  runs, regardless of which mechanism populates the submodule contents
  afterward.

- Native Linux/macOS/Windows (`Python package`) and Alpine Linux
  (`test-alpine`): tests pass as before. These platforms are not
  affected by the bug.

Each workflow's checkout step carries an inline comment pointing at PR
gitpython-developers#1715 so the temporary nature of the change is legible at a glance.

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: EliahKagan

.github/workflows/alpine-test.yml

@@ -29,6 +29,9 @@ jobs:
     - uses: actions/checkout@v6
       with:
         fetch-depth: 0
+        # Temporary, for testing. The standing decision is to NOT pre-clone
+        # submodules on CI; see https://github.com/gitpython-developers/GitPython/pull/1715
+        submodules: recursive
 
     - name: Set workspace ownership
       run: |

.github/workflows/cygwin-test.yml

@@ -39,6 +39,9 @@ jobs:
       uses: actions/checkout@v6
       with:
         fetch-depth: 0
+        # Temporary, for testing. The standing decision is to NOT pre-clone
+        # submodules on CI; see https://github.com/gitpython-developers/GitPython/pull/1715
+        submodules: recursive
 
     - &install-cygwin
       name: Install Cygwin

.github/workflows/pythonpackage.yml

@@ -53,6 +53,9 @@ jobs:
     - uses: actions/checkout@v6
       with:
         fetch-depth: 0
+        # Temporary, for testing. The standing decision is to NOT pre-clone
+        # submodules on CI; see https://github.com/gitpython-developers/GitPython/pull/1715
+        submodules: recursive
 
     - name: Set up Python ${{ matrix.python-version }}
       uses: actions/setup-python@v6