(including small changes to revert and backout to not show these stats
with the exception of backout --merge)
Show update stats (unless -q), e.g.:
K files updated, L files merged, M files removed, N files unresolved
Inform the user what to do after a merge:
(branch merge, don't forget to commit)
Inform the user what to do if a branch merge failed:
There are unresolved merges, you can redo the full merge using:
hg update -C X
hg merge Y
Inform the user what to do if a working directory merge failed:
There are unresolved merges with locally modified files.
Some systems show "Thu Jan 01" instead of "Thu Jan 1", which breaks tests.
Using "1000000" yields "Mon Jan 12 13:46:40 1970", which looks the same on
all systems.
