def get_repository_root(cls, location):
        # type: (str) -> Optional[str]
        """
        Return the "root" (top-level) directory controlled by the vcs,
        or `None` if the directory is not in any.

        It is meant to be overridden to implement smarter detection
        mechanisms for specific vcs.

        This can do more than is_repository_directory() alone. For
        example, the Git override checks that Git is actually available.
        """
        if cls.is_repository_directory(location):
            return location
        return None

        Return the "root" (top-level) directory controlled by the vcs,
        or `None` if the directory is not in any.

        It is meant to be overridden to implement smarter detection
        mechanisms for specific vcs.

        This can do more than is_repository_directory() alone. For
        example, the Git override checks that Git is actually available.
        
product/gradle-plugin/src/main/python/pip/_internal/vcs/versioncontrol.py