fix: make clone-cache copy tolerate symlinks and existing dirs

src/gitws/_pathlock.py

@@ -129,7 +129,9 @@ def atomic_update_or_create_path(path: Path):
             # If the path already exists, make a copy to work on:
             if path.exists():
                 if path.is_dir():
-                    copytree(path, tmp_path)
+                    # symlinks=True: preserve symlinks rather than dereference them, so a
+                    # dangling symlink in the source does not abort the copy with ENOENT.
+                    copytree(path, tmp_path, symlinks=True)
                 else:
                     copyfile(path, tmp_path)
 

src/gitws/git.py

@@ -356,7 +356,12 @@ def _clone_cache(self, url):
                 tmp_cache.mkdir(parents=True)
                 run(("git", "clone", "--", str(url), str(tmp_cache)))
             _LOGGER.debug("Copy %s to  %s)", tmp_cache, self.path)
-            shutil.copytree(tmp_cache, self.path)
+            # symlinks=True: a repo may contain a dangling symlink (e.g. edk2's
+            # EmulatorPkg X11IncludeHack); following it would abort the copy with ENOENT.
+            # dirs_exist_ok=True: self.path may be an empty submodule mountpoint left by a
+            # parent clone (the assert in clone() guarantees it is empty); plain git clone
+            # tolerates that, but copytree otherwise rejects it with FileExistsError.
+            shutil.copytree(tmp_cache, self.path, symlinks=True, dirs_exist_ok=True)
             # Remove user/password credentials from cache
             self._run(("remote", "remove", "origin"), cwd=tmp_cache)
 

tests/test_git.py

@@ -286,6 +286,46 @@ def test_cache_modified(tmp_path, repos):
     assert not (git.path / "new.txt").exists()
 
 
+def test_cache_dangling_symlink(tmp_path):
+    """A cached repo with a dangling symlink must clone without dereferencing it."""
+    repos_path = tmp_path / "repos"
+
+    with git_repo(repos_path / "main", commit="initial") as path:
+        (path / "data.txt").write_text("main")
+        (path / "dangling").symlink_to("does/not/exist")
+
+    cache_path = tmp_path / "cache"
+
+    # First clone initializes the cache: copytree cache -> destination.
+    git = Git(tmp_path / "main1", clone_cache=cache_path)
+    git.clone(path2url(repos_path / "main"))
+    assert (git.path / "dangling").is_symlink()
+
+    # Second clone reuses the cache: copytree cache -> tmp (pathlock), then -> destination.
+    git = Git(tmp_path / "main2", clone_cache=cache_path)
+    git.clone(path2url(repos_path / "main"))
+    assert (git.path / "dangling").is_symlink()
+
+
+def test_cache_existing_empty_dir(tmp_path):
+    """Cloning via the cache into an existing empty dir (submodule mountpoint) must work."""
+    repos_path = tmp_path / "repos"
+
+    with git_repo(repos_path / "main", commit="initial") as path:
+        (path / "data.txt").write_text("main")
+
+    cache_path = tmp_path / "cache"
+
+    # git leaves an empty directory for an uninitialised submodule mountpoint; the
+    # cache -> destination copy must merge into it instead of failing on its existence.
+    for name in ("main1", "main2"):  # cache-init, then cache-reuse
+        dest = tmp_path / name
+        dest.mkdir(parents=True)
+        git = Git(dest, clone_cache=cache_path)
+        git.clone(path2url(repos_path / "main"))
+        assert (git.path / "data.txt").read_text() == "main"
+
+
 def test_empty(tmp_path):
     """Test is_empty()."""
     Git.init(tmp_path)