Merge branch 'maint'

* maint:
  Documentation/SubmittingPatches: clarify GMail section and SMTP
  show-branch: use DEFAULT_ABBREV instead of 7
  t7502-commit: fix spelling
  test get_git_work_tree() return value for NULL

t/t7502-commit.sh

@@ -35,7 +35,7 @@ test_expect_success 'partial' '
 
 '
 
-test_expect_success 'partial modification in a subdirecotry' '
+test_expect_success 'partial modification in a subdirectory' '
 
 	test_tick &&
 	git commit -m "partial commit to subdirectory" not &&