[PATCH] pungi: allow building a self-hosting distribution

[Bill Nottingham]

The attached patch series allows pungi to build 'self-hosting' trees
by resolving all the build dependencies for a package set. It does
not expand the package set for the 'assumed' build depedencies such
as gcc; those are probably better specified in the kickstart file.

As an example, with this, 'pungi --selfhosting' of a kickstart
with just @Core yields over 1200 source packages, and over 500
source packages.

 bin/pungi.py        |    7 +++++-
 pypungi/__init__.py |   59 +++++++++++++++++++++++++++++++++++++---------------
 2 files changed, 48 insertions(+), 18 deletions(-)