merge: move dr/rd warning messages out of applyupdates()
As preparation for making 'dr' and 'rd' actions no longer actions,
move the reporting from applyupdates() to its caller update(). This
way we won't have to pass additonal arguments to applyupdates() when
they are no longer actions. Also, the warnings are equally unrelated
to applyupdates() as they are to recordupdates(), as they don't result
in any changes to either the working copy or the dirstate.
See earlier patch for additional motivation.
ERROR: FIXME: This is a known failure of filelog.size for data starting with \1\n
OK.