test_must_fail do_checkout branch2 $HEAD2
'
+test_expect_success 'checkout -b to @{-1} fails with the right branch name' '
+ git reset --hard HEAD &&
+ git checkout branch1 &&
+ git checkout branch2 &&
+ echo >expect "fatal: A branch named '\''branch1'\'' already exists." &&
+ test_must_fail git checkout -b @{-1} 2>actual &&
+ test_cmp expect actual
+'
+
test_expect_success 'checkout -B to an existing branch resets branch to HEAD' '
git checkout branch1 &&
test_cmp expect actual
'
+test_expect_success 'checkout -B to the current branch fails before merging' '
+ git checkout branch1 &&
+ setup_dirty_mergeable &&
+ git commit -mfooble &&
+ test_must_fail git checkout -B branch1 initial &&
+ test_must_fail test_dirty_mergeable
+'
+
test_done