[Distutils] factor out project metadata in PEP426?

[holger krekel]

Hi Nick, all,

PEP426 and its prior related peps see project-specific metadata as part
of distribution metadata.  Main examples are "project urls" such as
"home page", "repository", "issue tracker" or contact points such as
mailing lists, maintainer emails etc.  However, at any point in time
there is only one set of active project urls and contact points.
Putting those into distribution files does not really make sense.

I suggest to rather define "project metadata" and make distribution 
metadata reference it. Of course we then also want a simple way to
retrieve project metadata from pypi.  Which could be used from tools to 
tell a user where to send a mail to etc. ("pypi-report-bug warehouse" could
e.g. open the webbrowser with the create-issue page).  Or from PyPI
implementations to present proper project meta info even if looking
at an older version (the project might have switched to a different
repo meanwhile etc.)

It would also make life easier for project maintainers to change project
metadata even between releases.

I feel that PEP426 is a big chance to clean up the project/distribution
metadata confusion and provide a better base for future tooling and
organising human communication and collaboration around Python software.

cheers,
holger