make incoming work via ssh (issue139); move chunk code into separate module. 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.

abort: Connection refused
255
copy: No such file or directory
changeset:   0:53e17d176ae6
tag:         tip
user:        test
date:        Mon Jan 12 13:46:40 1970 +0000
summary:     test

requesting all changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
1 files, 1 changesets, 1 total revisions
foo
pulling from old-http://localhost:20059/remote
searching for changes
no changes found