hgweb: partially revert 4ec58b157265
The change from self.repo.ui.diffopts() to ui.diffopts() causes a
traceback when the diff of a changeset should be displayed in the
web interface. Revert to self.repo.ui.diffopts() for now.
changeset = '{rev}{tags}{parents} {node|short} {date|isodate} {author|user}\n {desc|firstline|strip}\n\n'
changeset_quiet = '{rev}:{node|short}\n'
start_tags = '['
tag = '{tag},'
last_tag = '{tag}]'
start_parents = ':'
parent = '{rev},'
last_parent = '{rev}'