Merge commit 'v1.7.2-rc0~6^2' into cc/cherry-pick-stdin

* commit 'v1.7.2-rc0~6^2': DWIM 'git show -5' to 'git show --do-walk -5' Documentation/SubmittingPatches: Fix typo in GMail section Documentation/config: describe status.submodulesummary This commit fixes one test in t3508 by making "cherry-pick -<num>" walk the history. A test update from Elijah Newren is squashed as an evil merge.