ngtip: fix TypeError: make revset from revs, not nodes (issue6405) This commit does two things: - Firstly, it tweaks the ngtip revset test to exercise the -G/--graph flag. This successfully triggers the bug when it is present. - Secondly, it changes the `ngtip` revset to return a revset made from integer revs instead of node hash bytes. The test now passes. Details: The TypeError was triggered by running hg log -r 'ngtip("default")' --graph in a repository with more than one changeset. The --graph tag caused the flow of control to call `reachableroots2` with the changeset ID found by the `ngtip` revset. Because the changeset ID was a node hash (bytes) instead of a rev (int), reachableroots2 raised the following error: TypeError: an integer is required (got type bytes)