'set-tree' probably accurately describes what the command
formerly known as 'commit' does.

I'm not entirely sure that 'dcommit' should be renamed to 'commit'
just yet...  Perhaps 'push' or 'push-changes'?
Signed-off-by: NEric Wong <normalperson@yhbt.net>
Signed-off-by: NJunio C Hamano <junkio@cox.net>