Sync with Git 2.6.6

* maint-2.6: Git 2.6.6 Git 2.5.5 Git 2.4.11

Junio C Hamano committed Mar 17, 2016 at 11:28 UTC 8e9cc5f3e2899fc4cfaf0c1ee039fb2c6683c0a9

No changes.