DIAG v4: minimal single-job diagnostic for fast turnaround

Replace the entire test-cygwin workflow with a single `diag` job that:
- Runs Cygwin's `git submodule update --init --recursive` (the actual
  thing that creates the disputed directories)
- Dumps Windows-side ACL via `Get-Acl`/`icacls` on each candidate path
- Dumps Cygwin-side `stat`/`getfacl`, `mount`, `getent passwd`
- Tries `git rev-parse` on each fixture, with the pre-fix
  `safe.directory` (only main repo and `.git`)
- Runs two controlled experiments: `chown` the gitdb worktree, then
  also `chown` `.git/modules/gitdb`, re-running `rev-parse` after
  each. Confirms whether ownership is the only blocker.

No pytest, no matrix, no extra setup steps. Should complete in ~2-3
minutes once a Cygwin runner picks it up, well ahead of the
v1/v2/v3 diags that are still queued behind the chain's matrix.

This branch should be deleted once the data is captured.

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

Author: EliahKagan

.github/workflows/cygwin-test.yml

@@ -6,131 +6,158 @@ permissions:
   contents: read
 
 jobs:
-  test:
-    strategy:
-      matrix:
-        selection: [fast, perf]
-        include:
-        - selection: fast
-          additional-pytest-args: --ignore=test/performance
-        - selection: perf
-          additional-pytest-args: test/performance
-
-      fail-fast: false
-
+  diag:
     runs-on: windows-latest
 
-    env: &cygwin-env
+    env:
       CHERE_INVOKING: "1"
       CYGWIN_NOWINPATH: "1"
 
-    defaults: &cygwin-defaults
+    defaults:
       run:
         shell: C:\cygwin\bin\bash.exe --login --norc -eo pipefail -o igncr "{0}"
 
     steps:
-    - &force-lf
-      name: Force LF line endings
+    - name: Force LF line endings
       run: |
-        git config --global core.autocrlf false  # Affects the non-Cygwin git.
-      shell: pwsh  # Do this outside Cygwin, to affect actions/checkout.
+        git config --global core.autocrlf false
+      shell: pwsh
 
-    - &checkout
-      uses: actions/checkout@v6
+    - uses: actions/checkout@v6
       with:
         fetch-depth: 0
 
-    - &install-cygwin
-      name: Install Cygwin
+    - name: Install Cygwin
       uses: cygwin/cygwin-install-action@v6
       with:
-        packages: git python39 python-pip-wheel python-setuptools-wheel python-wheel-wheel
-        add-to-path: false  # No need to change $PATH outside the Cygwin environment.
+        packages: git
+        add-to-path: false
 
-    - &verbose-output
-      name: Arrange for verbose output
-      run: |
-        # Arrange for verbose output but without shell environment setup details.
-        echo 'set -x' >~/.bash_profile
-
-    - &safe-directory
-      name: Special configuration for Cygwin git
+    - name: Configure Cygwin git safe.directory (PRE-FIX state, no submodule entries)
       run: |
         git config --global --add safe.directory "$(pwd)"
         git config --global --add safe.directory "$(pwd)/.git"
-        git config --global --add safe.directory "$(pwd)/git/ext/gitdb"
-        git config --global --add safe.directory "$(pwd)/git/ext/gitdb/gitdb/ext/smmap"
         git config --global core.autocrlf false
 
-    - &prepare-repo
-      name: Prepare this repo for tests
-      run: |
-        ./init-tests-after-clone.sh
-
-    - &git-identity
-      name: Set git user identity and command aliases for the tests
-      run: |
-        git config --global user.email "travis@ci.com"
-        git config --global user.name "Travis Runner"
-        # If we rewrite the user's config by accident, we will mess it up
-        # and cause subsequent tests to fail
-        cat test/fixtures/.gitconfig >> ~/.gitconfig
-
-    - &setup-venv
-      name: Set up virtual environment
+    - name: Initialize submodules (Cygwin git, recursive)
       run: |
-        python3.9 -m venv .venv
-        echo 'BASH_ENV=.venv/bin/activate' >>"$GITHUB_ENV"
+        git submodule update --init --recursive
 
-    - &update-pypa
-      name: Update PyPA packages
+    - name: DIAG — full ownership and ACL trace
+      shell: pwsh
       run: |
-        python -m pip install -U pip 'setuptools; python_version<"3.12"' wheel
-
-    - &install-deps
-      name: Install project and test dependencies
-      run: |
-        pip install '.[test]'
-
-    - name: Show version and platform information
-      run: |
-        uname -a
-        command -v git python
-        git version
-        python --version
-        python -c 'import os, sys; print(f"sys.platform={sys.platform!r}, os.name={os.name!r}")'
-
-    - name: Test with pytest (${{ matrix.additional-pytest-args }})
-      run: |
-        pytest --color=yes -p no:sugar --instafail -vv ${{ matrix.additional-pytest-args }}
-
-  reproduce-safe-dir:
-    strategy:
-      matrix:
-        run: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 191, 192, 193, 194, 195, 196, 197, 198, 199, 200, 201, 202, 203, 204, 205, 206, 207, 208, 209, 210, 211, 212, 213, 214, 215, 216, 217, 218, 219, 220, 221, 222, 223, 224, 225, 226, 227, 228, 229, 230, 231, 232, 233, 234, 235, 236, 237, 238, 239, 240, 241, 242, 243, 244, 245, 246, 247, 248, 249, 250, 251, 252, 253, 254, 255, 256]
-      fail-fast: false
-
-    runs-on: windows-latest
-
-    env: *cygwin-env
-
-    defaults: *cygwin-defaults
-
-    steps:
-    - *force-lf
-    - *checkout
-    - *install-cygwin
-    - *verbose-output
-    - *safe-directory
-    - *prepare-repo
-    - *git-identity
-    - *setup-venv
-    - *update-pypa
-    - *install-deps
-
-    - name: Run submodule tests
+        $repo = "D:\a\GitPython\GitPython"
+        Write-Host "==================== Windows-side ACL ===================="
+        $paths = @(
+          $repo,
+          "$repo\.git",
+          "$repo\git",
+          "$repo\git\ext",
+          "$repo\git\ext\gitdb",
+          "$repo\git\ext\gitdb\.git",
+          "$repo\.git\modules",
+          "$repo\.git\modules\gitdb",
+          "$repo\git\ext\gitdb\gitdb",
+          "$repo\git\ext\gitdb\gitdb\ext",
+          "$repo\git\ext\gitdb\gitdb\ext\smmap",
+          "$repo\git\ext\gitdb\gitdb\ext\smmap\.git",
+          "$repo\.git\modules\gitdb\modules",
+          "$repo\.git\modules\gitdb\modules\smmap"
+        )
+        foreach ($p in $paths) {
+          Write-Host "==== $p"
+          if (Test-Path -LiteralPath $p) {
+            $acl = Get-Acl -LiteralPath $p
+            Write-Host "Owner: $($acl.Owner)"
+            Write-Host "Group: $($acl.Group)"
+            $acl.Access | Where-Object { -not $_.IsInherited } | Format-Table IdentityReference, AccessControlType, FileSystemRights, InheritanceFlags, PropagationFlags -AutoSize
+            icacls $p
+          } else {
+            Write-Host "(does not exist)"
+          }
+          Write-Host ""
+        }
+
+    - name: DIAG — Cygwin-side ownership and rev-parse
       run: |
-        python -m pytest -vv \
-          test/test_docs.py::Tutorials::test_submodules \
-          test/test_repo.py::TestRepo::test_submodules \
-          test/test_submodule.py::TestSubmodule::test_root_module
+        set +e
+        echo "===================================================================="
+        echo "Cygwin user identity"
+        echo "===================================================================="
+        whoami
+        id
+        echo
+        echo "===================================================================="
+        echo "Cygwin: getent passwd"
+        echo "===================================================================="
+        getent passwd "$(whoami)" 2>&1
+        echo
+        echo "===================================================================="
+        echo "Mount info (look for ntsec/acl flags)"
+        echo "===================================================================="
+        mount
+        echo
+        echo "===================================================================="
+        echo "Per-path stat + getfacl"
+        echo "===================================================================="
+        for path in \
+          "$(pwd)" \
+          "$(pwd)/.git" \
+          "$(pwd)/git" \
+          "$(pwd)/git/ext" \
+          "$(pwd)/git/ext/gitdb" \
+          "$(pwd)/git/ext/gitdb/.git" \
+          "$(pwd)/.git/modules" \
+          "$(pwd)/.git/modules/gitdb" \
+          "$(pwd)/git/ext/gitdb/gitdb" \
+          "$(pwd)/git/ext/gitdb/gitdb/ext" \
+          "$(pwd)/git/ext/gitdb/gitdb/ext/smmap" \
+          "$(pwd)/git/ext/gitdb/gitdb/ext/smmap/.git" \
+          "$(pwd)/.git/modules/gitdb/modules" \
+          "$(pwd)/.git/modules/gitdb/modules/smmap"; do
+          echo "--- $path"
+          stat -c 'uid=%u(%U) gid=%g(%G) mode=%a type=%F' "$path" 2>&1
+          if [ -f "$path" ]; then
+            echo "(gitlink content):"
+            cat "$path"
+            echo
+          fi
+          getfacl --absolute-names "$path" 2>&1 | sed 's/^/  /' | head -15
+          echo
+        done
+        echo
+        echo "===================================================================="
+        echo "git rev-parse on each fixture (PRE-FIX safe.directory)"
+        echo "===================================================================="
+        for fixture in "$(pwd)" "$(pwd)/git/ext/gitdb" "$(pwd)/git/ext/gitdb/gitdb/ext/smmap"; do
+          echo "--- $fixture"
+          git -C "$fixture" rev-parse --show-toplevel 2>&1
+          echo "(rc=$?)"
+        done
+        echo
+        echo "===================================================================="
+        echo "Controlled experiment: chown gitdb worktree, then re-test"
+        echo "===================================================================="
+        chown -R "$(id -u):$(id -g)" "$(pwd)/git/ext/gitdb" 2>&1 | head -5
+        echo "After chown of $(pwd)/git/ext/gitdb:"
+        stat -c '  uid=%u(%U) %n' "$(pwd)/git/ext/gitdb"
+        echo
+        for fixture in "$(pwd)/git/ext/gitdb" "$(pwd)/git/ext/gitdb/gitdb/ext/smmap"; do
+          echo "--- $fixture"
+          git -C "$fixture" rev-parse --show-toplevel 2>&1
+          echo "(rc=$?)"
+        done
+        echo
+        echo "===================================================================="
+        echo "Controlled experiment: chown .git/modules/gitdb, then re-test"
+        echo "===================================================================="
+        chown -R "$(id -u):$(id -g)" "$(pwd)/.git/modules/gitdb" 2>&1 | head -5
+        echo "After chown of $(pwd)/.git/modules/gitdb:"
+        stat -c '  uid=%u(%U) %n' "$(pwd)/.git/modules/gitdb"
+        echo
+        for fixture in "$(pwd)/git/ext/gitdb" "$(pwd)/git/ext/gitdb/gitdb/ext/smmap"; do
+          echo "--- $fixture"
+          git -C "$fixture" rev-parse --show-toplevel 2>&1
+          echo "(rc=$?)"
+        done
+        true