context: be even more careful about result order in ancestors() (
issue2642)
The earlier patch could be confused by more complicated topologies.
basic test for hg debugrebuildstate
$ hg init repo
$ cd repo
$ touch foo bar
$ hg ci -Am 'add foo bar'
adding bar
adding foo
$ touch baz
$ hg add baz
$ hg rm bar
$ hg debugrebuildstate
state dump after
$ hg debugstate --nodates | sort
n 666 -1 bar
n 666 -1 foo
status
$ hg st -A
! bar
? baz
C foo