Bug#488424: should delete cached files that don't verify

[Frans Pop <elendil@planet.nl>]

tag 488424 pending
thanks

On Tuesday 01 July 2008, Joey Hess wrote:
> Frans Pop wrote:
> > What about something like the attached (untested) patch?
> >
> > It ensures that both the Release and Release.gpg files are always
> > downloaded.
>
> That's perfectly reasonable. I think it's ok to not cache these even if
> they are good, because it prevents running debootstrap later with an
> out of date Release file

OK. Tested and committed.

I had to make an additional change as the "nocache" option was being used 
as md5sum, which obviously won't work :-P

While testing I also noticed that if all variants (.gz, .bz2) of a 
Packages file fail to verify because their md5sums don't match what's 
listed in the Release file, debootstrap did not abort. It would fail 
later on, but with a rather vague error.
I also added a test for that (re-using an existing error code).

Cheers,
FJP