cleanups in revlog.lookup
- add comments
- do a clean separation of the different cases
- don't use a list of each possible node when
doing the lookup, just keep the previous entry
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
abort: Permission denied: test-ro-message/b/vehicle