revset: special case commonancestors(none()) to be empty set
This matches the behavior of ancestor(none()).
From an implementation perspective, ancestor() and commonancestors() are
intersection, and ancestors() is union, so it would make some sense that
commonancestors(none()) returned all revisions. However, ancestor(none())
isn't implemented as such, which breaks ancestor(x) == max(commonancestors(x)).
From a user perspective, ancestors of nothing is nothing whichever type
of operation the ancestor predicate does.
#!/usr/bin/env python
#
# An example hgweb CGI script, edit as necessary
# See also https://mercurial-scm.org/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)