git reflog exists refs/heads/n
'
+# The topmost entry in reflog for branch bbb is about branch creation.
+# Hence, we compare bbb@{1} (instead of bbb@{0}) with aaa@{0}.
+
+test_expect_success 'git branch -m bbb should rename checked out branch' '
+ test_when_finished git branch -D bbb &&
+ test_when_finished git checkout master &&
+ git checkout -b aaa &&
+ git commit --allow-empty -m "a new commit" &&
+ git rev-parse aaa@{0} >expect &&
+ git branch -m bbb &&
+ git rev-parse bbb@{1} >actual &&
+ test_cmp expect actual &&
+ git symbolic-ref HEAD >actual &&
+ echo refs/heads/bbb >expect &&
+ test_cmp expect actual
+'
+
test_expect_success 'git branch -m o/o o should fail when o/p exists' '
git branch o/o &&
git branch o/p &&