test(stats): avoid normalizing fixture paths on Windows

The stats regression's root and modification assertions pass on Windows,
but IndexFile.remove normalizes the all-space test path to `.` and makes
`git rm` fail before testing deletion statistics.

Clear and write the fixture's in-memory index instead, just as the test
already stores its initial blobs directly. The resulting empty-tree
commit still exercises deletion statistics for every original filename.

The full Linux suite again passes: 1690 passed, 89 skipped, 1 xfailed,
and 64 subtests. Focused commit/util/diff tests, pre-commit, mypy, and
basedpyright pass. Windows CI will verify the portability correction.

Prepared by OpenAI Codex (dot); human review is pending.

Author: v1shay

test/test_commit.py

@@ -189,7 +189,10 @@ def test_stats_preserve_filename_spaces(self, rw_dir):
         assert empty_stats.files == {}
         assert empty_stats.total == {"insertions": 0, "deletions": 0, "lines": 0, "files": 0}
 
-        repo.index.remove(list(paths))
+        # Avoid filesystem path normalization of space-only names on Windows.
+        index = repo.index
+        index.entries.clear()
+        index.write()
         removed_stats = repo.index.commit("Remove files", author=actor, committer=actor).stats
         assert removed_stats.files == {
             path: {"insertions": 0, "deletions": 2 * count, "lines": 2 * count, "change_type": "D"}