clone: allow bundle2's stream clone with 'server.disablefullbundle'

The previous check was a bit too strict and would not recognize a get bundle
not requesting changegroup.

mercurial/wireproto.py

@@ -866,10 +866,11 b' def getbundle(repo, proto, others):'
         if repo.ui.configbool('server', 'disablefullbundle'):
             # Check to see if this is a full clone.
             clheads = set(repo.changelog.heads())
+            changegroup = opts.get('cg', True)
             heads = set(opts.get('heads', set()))
             common = set(opts.get('common', set()))
             common.discard(nullid)
-            if not common and clheads == heads:
+            if changegroup and not common and clheads == heads:
                 raise error.Abort(
                     _('server has pull-based clones disabled'),
                     hint=_('remove --pull if specified or upgrade Mercurial'))