revlog: do inclusive descendant testing (API)
In many other places, a revision is considered a descendant of itself. We
update the behavior of `revlog.descendant()` to match this. (for example.
`revlog.isancestor` does inclusive testing).
No tests break, so it seems safe to do so.
This will make it easier to use a more efficient implementation in a later
changeset.
Hello, Foobar
[b'Hello, Fo, =;:<o', b'Hello, Bar']