commit: allow --amend to reuse message from another commit
After tentatively applying a patch from a contributor, you can get a
replacement patch with corrected code and unusable commit log message.
In such a case, this sequence ought to give you an editor based on the
message in the earlier commit, to let you describe an incremental
improvement:
git reset --hard HEAD^ ;# discard the earlier one
git am <corrected-patch
git commit --amend -c HEAD@{1}
Unfortunately, --amend insisted reusing the message from the commit
being amended, ignoring the -c option. This corrects it.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/t/t7501-commit.sh b/t/t7501-commit.sh
index 05aa97d..d1a415a 100755
--- a/t/t7501-commit.sh
+++ b/t/t7501-commit.sh
@@ -310,4 +310,21 @@
'
+test_expect_success 'amend using the message from another commit' '
+
+ git reset --hard &&
+ test_tick &&
+ git commit --allow-empty -m "old commit" &&
+ old=$(git rev-parse --verify HEAD) &&
+ test_tick &&
+ git commit --allow-empty -m "new commit" &&
+ new=$(git rev-parse --verify HEAD) &&
+ test_tick &&
+ git commit --allow-empty --amend -C "$old" &&
+ git show --pretty="format:%ad %s" "$old" >expected &&
+ git show --pretty="format:%ad %s" HEAD >actual &&
+ diff -u expected actual
+
+'
+
test_done
