When "hg pull --rebaseif" needs to do a merge instead of a rebase, it always leaves it up to the user to commit that merge, even when it resolved cleanly automatically. This is a little annyoing, since when rebaseif ends with a merge, I always end up doing "hg resolve -l", "oh, everything's resolved already", "hg ci -m 'Merge upstream'". That's what computers are for, aren't they? ;-)
The stock "hg fetch" extension (which does pull+merge) automatically commits the merge if there are no conflicts. It would be handy if rebaseif did the same, i.e. attempt to rebase, if that fails to go cleanly, do a merge -- but if that works cleanly, commit it automatically.