> We already have authors and maintainers (which causes confusion), 
> adding yet another field for contributors is overkill,

Not on the Metadata side though. That's only on setup() side. The
resulting metadata only contains "Author" and "Author-email", and it's
calculated using 'author' *or* 'maintainer' arguments. Meaning that when
you fill both, one is lost. (and leading to the current inconsistency).

So being able to have several Authors (not yet another field, an
existing one, but multi-valued) and an "authors" argument would fix this
inconsistency since we would be able to keep both.

This is not a big change on the metadata format, it just means that we
can have extra "Author:" lines, so it's backward compatible.

OTHO, deprecating "maintainer" and "maintainer_email" on setup() side,
and making it clear that there's only one Author and one email could
work too.