Clean metadata from a TarInfo object to make it more reproducible.

            - Set uid & gid to 0
            - Set uname and gname to ""
            - Normalise permissions to 644 or 755
            - Set mtime if not None

def clean_tarinfo(cls, tar_info):
        """
        Clean metadata from a TarInfo object to make it more reproducible.

            - Set uid & gid to 0
            - Set uname and gname to ""
            - Normalise permissions to 644 or 755
            - Set mtime if not None
        """
        ti = copy(tar_info)
        ti.uid = 0
        ti.gid = 0
        ti.uname = ""
        ti.gname = ""
        ti.mode = normalize_file_permissions(ti.mode)

        return ti