Merge branch 'kn/for-each-branch'

Using the timestamp based criteria in "git branch --sort" did not
tiebreak branches that point at commits with the same timestamp (or
the same commit), making the resulting output unstable.

* kn/for-each-branch:
  ref-filter: fallback on alphabetical comparison

t/t3203-branch-output.sh

@@ -158,8 +158,8 @@ EOF
 
 test_expect_success 'git branch `--sort` option' '
 	cat >expect <<-\EOF &&
-	  branch-two
 	* (HEAD detached from fromtag)
+	  branch-two
 	  branch-one
 	  master
 	EOF