Incoming ssh needs to detect the end of the changegroup, otherwise it would
block trying to read from the ssh pipe. This is done by parsing the
changegroup chunks.
bundlerepo.getchunk() already is identical to
localrepo.addchangegroup.getchunk(), which is followed by getgroup which
looks much like what you can re-use in bundlerepository.__init__() and in
write_bundle(). bundlerevlog.__init__.genchunk() looks very similar, too,
as do some while loops in localrepo.py.
Applied patch from Benoit Boissinot to move duplicate/related code
to mercurial/changegroup.py and use this to fix incoming ssh.
