Report on push/pull if heads are merged, too, like for new heads.
Use case: If a remote repo has two heads and I _want_ to merge them, I merge
and push. Meanwhile someone else pushed on top of one of the heads. He won't
get a warning, because he doesn't create a new head, I won't notice that I
don't close a head, because I don't get a message telling me.
adding a
adding b
0
0
0
a: No such file in rev 03f6b0774996
1