code: def _is_always_unsatisfied(self):
          
          # If this is a github sha tarball, then it is always unsatisfied
          # because the url has a commit sha in it and not the version
          # number.
          url = self._url()
          if url:
              filename = filename_from_url(url)
              if filename.endswith(ARCHIVE_EXTENSIONS):
                  filename, ext = splitext(filename)
                  if is_git_sha(filename):
                      return True
          return False
docs: Returns whether this requirement is always unsatisfied
  
          This would happen in cases where we can't determine the version
          from the filename.