+test_expect_success 'merge base test setup' '
+ git checkout -b another other &&
+ echo "hello again" >>world &&
+ git add world &&
+ git commit -m third
+'
+
+test_expect_success 'another...master' '
+ git checkout another &&
+ git checkout another...master &&
+ test "z$(git rev-parse --verify HEAD)" = "z$(git rev-parse --verify master^)"
+'
+
+test_expect_success '...master' '
+ git checkout another &&
+ git checkout ...master &&
+ test "z$(git rev-parse --verify HEAD)" = "z$(git rev-parse --verify master^)"
+'
+
+test_expect_success 'master...' '
+ git checkout another &&
+ git checkout master... &&
+ test "z$(git rev-parse --verify HEAD)" = "z$(git rev-parse --verify master^)"
+'
+