backout: clarify which changesets are new in help text
Plus another wording tweak ("default behavior -> "behavior without
--merge").
Suggested by Kevin Bullock.
context: generate file ancestors in reverse revision order (
issue2642)
The related() function in copies assumes that revisions are generated
in reverse revision order, so it was getting confused in some situations.
subrepo: only attempt pulling from git's origin
git fetch does not accept repository URLs as arguments, and the intended
logic of this code was not actually doing anything.