chgserver: use global ui instead of repo ui for dispatch.request.ui...
chgserver: use global ui instead of repo ui for dispatch.request.ui
Before this patch, chgserver will use repo ui as dispatch.request.ui, while
req.ui is designed to be global ui without repo config.
Passing repo ui as dispatch.request.ui leads to repo.ui being incorrect, which
can lead to unwanted results. For example, if the repo config has [extensions],
it could affect which localrepository.featuresetupfuncs get executed and the
repo may have an incorrect list of supported requirements.
This patch changes _renewui to return both global ui and repo ui. The global
ui is passed to req.ui, and the repo ui is used to calculate confighash. It
will make chg pass test-largefiles-misc.t and test-requires.t, which are both
related to repo requirements.
