This had the unfortunate side effect of causing the environment to have a
newline due to the fact that some 'cd' outputs the result of the directory
change. So, let's just redirect the meaningless output.
This allows builddeb to handle distributions that are not Debian.
Distributor ID is reported by lsb_release --id, and in case of builddeb it's
usually Debian or Ubuntu.
Debian and Ubuntu releases have both codenames and traditional version numbers.
An entire "branch" of releases is referred to by its codename, and version
numbers (e.g. 8.2, 14.04.3) are used to address individual releases.
Since we use codenames for building .deb packages, let's call the option and
the variable appropriately.
This is a much larger commit than I'd like, but I honestly don't see a
good way to break it up and leave things working. Summary:
We now use debian/rules with debhelper to build our debs. This is much
more standard, and means we use dh_python2 to do things like handle
leaving .pyc files out of the built debs.
The resulting package is split into mercurial and mercurial-common,
with the former being the hg stub and all the native .sos, and the
latter being basically everything else.
builddeb and dockerdeb are updated to use the new system. The old way
(using dpkg by hand) breaks with the above changes because
debian/control no longer contains a version string (that's now guessed
from the phony changelog.)
Tests are updated to assert that the right files end up in the right
debs.
