git-commit: Allow to amend a merge commit that does not change the tree

diff --git a/t/t7501-commit.sh b/t/t7501-commit.sh
index 31a6f63399a97902e493c453a3f3117bc44ef2f7..2e7bcb016ac94f150423446b2fbce2d61eb7bced 100755 (executable)
--- a/t/t7501-commit.sh
+++ b/t/t7501-commit.sh
@@ -244,4 +244,36 @@ test_expect_success 'multiple -m' '
 
 '
 
+test_expect_success 'same tree (single parent)' '
+
+       if git commit -m empty
+       then
+               echo oops -- should have complained
+               false
+       else
+               : happy
+       fi
+
+'
+
+test_expect_success 'same tree (merge and amend merge)' '
+
+       git checkout -b side HEAD^ &&
+       echo zero >zero &&
+       git add zero &&
+       git commit -m "add zero" &&
+       git checkout master &&
+
+       git merge -s ours side -m "empty ok" &&
+       git diff HEAD^ HEAD >actual &&
+       : >expected &&
+       diff -u expected actual &&
+
+       git commit --amend -m "empty really ok" &&
+       git diff HEAD^ HEAD >actual &&
+       : >expected &&
+       diff -u expected actual
+
+'
+
 test_done