bisect extension for mercurial
it works almost the same as git-bisect:
hg bisect init # start bisecting
hg bisect bad # mark current revision as broken
hg bisect good [<rev>] # mark <rev> as working
... the bisect code finds a new revision to try
... see if it works
hg bisect good # if it worked
hg bisect bad # it doesn't work
continue until there is only one revision left