def can_patch(self, filename):
    """ Check if specified filename can be patched. Returns None if file can
    not be found among source filenames. False if patch can not be applied
    clearly. True otherwise.

    :returns: True, False or None
    """
    filename = abspath(filename)
    for p in self.items:
      if filename == abspath(p.source):
        return self._match_file_hunks(filename, p.hunks)
    return None
Check if specified filename can be patched. Returns None if file can
    not be found among source filenames. False if patch can not be applied
    clearly. True otherwise.

    :returns: True, False or None