fix(repo): unquote the filename line in Repo.blame_incremental

`Repo.blame_incremental` took `BlameEntry.orig_path` from the `filename`
line of `git blame --incremental` verbatim. Git writes that line with
`write_name_quoted`, so a path containing a double quote, a backslash, a
control character or, with the default `core.quotePath=true`, any
non-ASCII byte is C-quoted: a line attributed to `café.txt` came back as
`orig_path == '"caf\303\251.txt"'` and `"quoted".txt` as
`'"\\"quoted\\".txt"'`, names that exist nowhere in the repository.
The quoted form reaches callers whenever the blamed file was renamed
from such a name, which the author of the history chooses.

Decode a quoted `filename` value with the existing `_unquote_path`
helper from `git.diff`, which already reverses Git's quoting for diff
headers; unquoted values are unchanged. The non-incremental porcelain
parser in `Repo.blame` reads the same line but does not expose it, so
it needs no change.

Adds a `blame-quoted-filename` case to `tests/fixtures/repo.sh` and
`test_blame_incremental_unquotes_filenames` in `test/test_repo.py`,
which fails before the change and passes after on both the CLI and the
Gix backend. Ruff, mypy and ShellCheck pass.

Author: Keerthana-64

git/repo/base.py

@@ -1293,6 +1293,8 @@ def blame_incremental(
         If you combine all line number ranges outputted by this command, you should get
         a continuous range spanning all line numbers in the file.
         """
+        from git.diff import _unquote_path
+
         if not allow_unsafe_options:
             Git.check_unsafe_options(
                 options=Git._option_candidates([rev], kwargs),
@@ -1375,6 +1377,10 @@ def blame_incremental(
                         orig_filename = value
                         break
 
+            # Git C-quotes a filename containing control, quote, backslash or,
+            # with core.quotePath, non-ASCII bytes, the way it does in diff output.
+            if orig_filename.startswith(b'"') and orig_filename.endswith(b'"'):
+                orig_filename = _unquote_path(orig_filename[1:-1])
             yield BlameEntry(
                 commits[hexsha],
                 range(lineno, lineno + num_lines),

test/test_repo.py

@@ -792,6 +792,17 @@ def test_blame_content_with_carriage_returns(self):
             self.assertEqual(blames[0][0].author.name, "GitPython Tests")
             self.assertEqual(blames[0][1], ["first", forged])
 
+    def test_blame_incremental_unquotes_filenames(self):
+        # Git C-quotes the filename line of its incremental output for a path with
+        # non-ASCII, control, quote or backslash bytes. The entry must name the path.
+        for name in ("caf\u00e9.txt", '"quoted".txt', "tab\tname.txt", "back\\slash.txt"):
+            with self.subTest(name=name), fixture_repo("repo.sh", "blame-quoted-filename", name) as repo:
+                quoted = repo.git.blame("HEAD", "-p", "--incremental", "--", "plain.txt", stdout_as_string=False)
+                assert b'\nfilename "' in quoted
+                entries = list(repo.blame_incremental("HEAD", "plain.txt"))
+                self.assertEqual([entry.orig_path for entry in entries], [name])
+                self.assertEqual([entry.linenos for entry in entries], [range(1, 3)])
+
     def test_untracked_files(self):
         for command in ("index", "git"):
             with fixture_repo("repo.sh", "untracked", write=True) as repo:

tests/fixtures/repo.sh

@@ -123,6 +123,14 @@ blame-carriage-returns)
     git -C repo add file.txt
     git -C repo commit -qm init --author='GitPython Tests <gitpython@example.com>'
     ;;
+blame-quoted-filename)
+    git init -q repo
+    printf 'first\nsecond\n' > "repo/$2"
+    git -C repo add -- "$2"
+    git -C repo commit -qm init --author='GitPython Tests <gitpython@example.com>'
+    git -C repo mv -- "$2" plain.txt
+    git -C repo commit -qm rename --author='GitPython Tests <gitpython@example.com>'
+    ;;
 relocated-git-dir)
     git init -q repo
     mv repo/.git repo/.real