Keep bare-repository worktrees non-bare

.github/workflows/cygwin-test.yml

@@ -45,7 +45,7 @@ jobs:
     - name: Install Cygwin
       uses: cygwin/cygwin-install-action@v6
       with:
-        packages: git python39 python-pip-wheel python-setuptools-wheel python-wheel-wheel
+        packages: curl git python39 python-setuptools-wheel
         add-to-path: false  # No need to change $PATH outside the Cygwin environment.
 
     - name: Arrange for verbose output
@@ -73,12 +73,15 @@ jobs:
 
     - name: Set up virtual environment
       run: |
+        pip_wheel=/usr/share/python-wheels/pip-26.0.1-py3-none-any.whl
+        curl -fsSLo "$pip_wheel" https://files.pythonhosted.org/packages/de/f0/c81e05b613866b76d2d1066490adf1a3dbc4ee9d9c839961c3fc8a6997af/pip-26.0.1-py3-none-any.whl
+        python3.9 -c 'import hashlib, pathlib, sys; assert hashlib.sha256(pathlib.Path(sys.argv[1]).read_bytes()).hexdigest() == sys.argv[2]' "$pip_wheel" bdb1b08f4274833d62c1aa29e20907365a2ceb950410df15fc9521bad440122b
         python3.9 -m venv .venv
         echo 'BASH_ENV=.venv/bin/activate' >>"$GITHUB_ENV"
 
     - name: Update PyPA packages
       run: |
-        python -m pip install -U pip 'setuptools; python_version<"3.12"' wheel
+        python -m pip install -U 'setuptools; python_version<"3.12"' wheel
 
     - name: Install project and test dependencies
       run: |

git/repo/base.py

@@ -386,6 +386,10 @@ def __init__(
             # Let's not assume the option exists, although it should.
             pass
 
+        # A linked worktree is not bare even when its main repository is.
+        if self._bare and self._working_tree_dir and osp.isfile(osp.join(self.git_dir, "commondir")):
+            self._bare = False
+
         # Adjust the working directory in case we are actually bare - we didn't know
         # that in the first place.
         if self._bare:

test/test_repo.py

@@ -1459,6 +1459,23 @@ def test_git_work_tree_dotgit(self, rw_dir, use_relative_paths=False):
 
         self.assertIsInstance(repo.heads["aaaaaaaa"], Head)
 
+    @with_rw_directory
+    def test_git_work_tree_from_bare_repo(self, rw_dir):
+        if Git().version_info[:3] < (2, 5, 1):
+            pytest.skip("worktree feature unsupported, needs git 2.5.1 or later")
+
+        bare_repo = self.rorepo.clone(join_path_native(rw_dir, "bare_repo"), bare=True)
+        worktree_path = join_path_native(rw_dir, "worktree_repo")
+        if Git.is_cygwin():
+            worktree_path = cygpath(worktree_path)
+        bare_repo.git.worktree("add", "--detach", worktree_path)
+
+        repo = Repo(worktree_path)
+
+        assert Git(worktree_path).rev_parse("--is-bare-repository") == "false"
+        assert not repo.bare
+        assert osp.samefile(repo.working_tree_dir, worktree_path)
+
     def test_git_work_tree_dotgit_relative(self):
         """Check that we find .git as a worktree file containing a relative path
         and find the worktree based on it."""