patch: git metadata was ignored if strip > 1
gitpatch objects emitted by iterhunks() are modified in place by applydiff().
Processing them earlier improves iterhunks() isolation. applydiff() modifying
them should still be fixed though.
Ancestors of 5
4 2 0
Ancestors of 6 and 5
3 4 2 1 0
Ancestors of 5 and 4
4 2 0
Descendants of 5
7 8
Descendants of 5 and 3
6 7 8
Descendants of 5 and 4
5 7 8