This will trigger the filecache and recreate every cached property that was
changed by something other than this cmdserver instance (e.g. by running
'hg commit' at the cmdline).
The ui passed to server() is really repo.ui, that is it contains its local
configuration as well.
When running commands that use a different repo than the servers cached repo,
we don't want to use that ui as the baseui for the new repo.
