bug#17625: 24.4.50; All installed packages marked "unsigned", no archive listed

[Stefan Monnier]

> The mechanism by which they are supposed to do so seems completely
> undocumented (it's not even mentioned in NEWS), so I have no idea how they
> are expected to do so.

Indeed.  I think there are several bugs here, which we should fix before the
24.4 release:
- the "unsigned" thingy (is this supposed to check the signature of
  installed packages?  How could that work?  I thought we wanted to
  check the signature *during* installation).
- the fact that GNU ELPA's packages aren't signed.
- the fact that the expected signature format is not documented.


        Stefan