Proof cannot report that the maintainer field is wrong

[Curtis Hovey]

The majority of charms with errors list bogus maintainers. Authors commonly fork charms without correcting the maintainer field. Charmworld or users might want to contact authors, but it is not possible.

Proof could check for an author email in the env, such as EMAIL or DEBEMAIL and warn when the maintainer field cannot be confirmed. Charmworld's ingest process cannot use such a solution though. Maybe it could pass the branch location to proof to do a sanity check -- this is fraught with problems because anonymous process cannot see Lp email addresses and teams rarely have email addresses.

In general, we don't want to see Mimms and Ceppi blamed when someone else made the mistake.