Base binary packages using xz instead of gzip

[Guillem Jover <guillem@debian.org>]

Hi!

It seems there's quite many binary packages in the base system using
xz as compressor instead of gzip, since the switch to xz as default,
which might make debootstrapping from non-Debian systems harder. After
running the follwing:

  $ debootstrap --download-only sid sid-root-path
  $ cd sid-root-path
  $ find -name '*.deb' | while read deb; do \
      if ar t $deb | grep -q data\.tar\.$COMP; then \
        echo $deb; \
      fi \
    done | sort

with COMP=xz gives 145 packages, with COMP=gz it gives 21. So I guess
it would make sense to decide if people still care about bootstrapping
from other systems where xz-utils might not be available. I think a
lintian check would be pretty easy (which could key on the Priority of
the packages), and might help people to know when to compress using
gzip, as long as the archive override is kept up-to-date, that is
(I've to file some bugs about that).

Thanks,
Guillem