revlog.py: always return tuples from parents and parentrevs
There's at least one place doing parentrevs(rev) != (rev-1, -1),
which is always true with revlog v0, since parentrevs returns a list
in this case.
1 files updated, 0 files merged, 0 files removed, 0 files unresolvedremoving babort: update spans branches, use 'hg merge' or 'hg update -C' to lose changes