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.
http://mercurial.selenic.com/bts/issue433
$ hg init
$ echo a > a
$ hg commit -Ama
adding a
$ hg parents -r 0 doesnotexist
abort: 'doesnotexist' not found in manifest!
[255]