_to_relative_path to support mixing slashes and backslashes

Working on Windows you sometime end up having some paths with backslashes (windows native) and some with slashes - this PR will resolve the issue using gitpython for those kind of cases (see example below). It will also fix the issues if paths contain redundant separators or "..". ``` import git repo = git.Repo(r"C:\gittest") repo.index.add(r"C:\gittest\1.txt") # Traceback (most recent call last): # File "c:\second_test.py", line 5, in <module> # repo.index.add(r"C:/gittest/2.txt") # File "Python311\Lib\site-packages\git\index\base.py", line 879, in add # paths, entries = self._preprocess_add_items(items) # ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ # File "Python311\Lib\site-packages\git\index\base.py", line 672, in _preprocess_add_items # paths.append(self._to_relative_path(item)) # ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ # File "Python311\Lib\site-packages\git\index\base.py", line 657, in _to_relative_path # raise ValueError("Absolute path %r is not in git repository at %r" % (path, self.repo.working_tree_dir)) # ValueError: Absolute path 'C:/gittest/2.txt' is not in git repository at 'C:\\gittest' repo.index.add(r"C:/gittest/2.txt") repo.index.commit("test") ```

Author: Andrej730

git/index/base.py

@@ -653,7 +653,7 @@ def _to_relative_path(self, path: PathLike) -> PathLike:
 returnpath
 ifself.repo.bare:
 raiseInvalidGitRepositoryError("require non-bare repository")
-ifnotstr(path).startswith(str(self.repo.working_tree_dir)):
+ifnotosp.normpath(str(path)).startswith(osp.normpath(str(self.repo.working_tree_dir))):
 raiseValueError("Absolute path %r is not in git repository at %r"% (path, self.repo.working_tree_dir))
 returnos.path.relpath(path, self.repo.working_tree_dir)