[PATCH 1/2] Test case that demonstrates problem with --merge-order ^ processing

Added a test case that shows that --merge-order doesn't produce the
correct result in the following case.

A
|
| B
|/
C
|
D

git-rev-list --merge-order A ^B should produce just A. Instead
it produces BCD.

A subsequent patch will fix this defect.

Signed-off-by: Jon Seymour <redacted>
---

 t/t6001-rev-list-merge-order.sh |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

444e7b2e2491309cd7101bd48881743a35837a56

diff --git a/t/t6001-rev-list-merge-order.sh b/t/t6001-rev-list-merge-order.sh
--- a/t/t6001-rev-list-merge-order.sh
+++ b/t/t6001-rev-list-merge-order.sh

@@ -543,6 +543,11 @@ test_output_expect_success 'simple merge
 = alt_root
 EOF
 
+test_output_expect_success "don't print things unreachable from one branch" "git-rev-list a3 ^b3 --merge-order" <<EOF
+a3
+a2
+a1
+EOF
 
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