[Catalog-sig] Deprecation warnings on PyPI

["Martin v. Löwis"]

> That would work but I'd rather have someone searching for gitlsfiles
> on PyPI be told that it's deprecated than to let him try new keywords
> until he gives up and decides to try the other git plugin for
> setuptools.

In that case, it would probably best if the new plugin mentions that
it is a replacement for gitlsfiles. Then searching for gitlsfiles would
directly bring up the new plugin.

Regards,
Martin