bundle2: fix bundle2 pulling all revs on empty pulls
When bundle2 was enabled, if hg pull had no commits to pull, it would print
'no changes found' and then download the entire repository from the server. This
was caused by heads and common being set to None, which gets treated as
heads=cl.heads() and common=[nullid], which means download the entire repo.
Pulling bundles without a changegroup is a valid use case (like if we're just
updating bookmarks), so this modifes the bundle code to allow not adding
changegroups.
This is backport of ab5040cd5749.
#!/usr/bin/env python
#
# An example hgweb CGI script, edit as necessary
# See also http://mercurial.selenic.com/wiki/PublishingRepositories
# Path to repo or hgweb config to serve (see 'hg help hgweb')
config = "/path/to/repo/or/config"
# Uncomment and adjust if Mercurial is not installed system-wide
# (consult "installed modules" path from 'hg debuginstall'):
#import sys; sys.path.insert(0, "/path/to/python/lib")
# Uncomment to send python tracebacks to the browser if an error occurs:
#import cgitb; cgitb.enable()
from mercurial import demandimport; demandimport.enable()
from mercurial.hgweb import hgweb, wsgicgi
application = hgweb(config)
wsgicgi.launch(application)