[PATCH] cherry-pick -x: improve handling of one-liner commit messages

[Miklos Vajna <vmiklos@suse.cz>]

git cherry-pick -x normally just appends the "cherry picked from commit"
line at the end of the message, which is fine. However, in case the
original commit message had only one line, first append a newline,
otherwise the second line won't be empty, which is against
recommendations.
---
 sequencer.c                   | 10 ++++++++++
 t/t3501-revert-cherry-pick.sh |  8 ++++++++
 2 files changed, 18 insertions(+)

diff --git a/sequencer.c b/sequencer.c
index aef5e8a..1ae0e43 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -496,6 +496,16 @@ static int do_pick_commit(struct commit *commit, struct replay_opts *opts)
 		}
 
 		if (opts->record_origin) {
+
+			/*
+			 * If this the message is a one-liner, append a
+			 * newline, so the second line will be empty, as
+			 * recommended.
+			 */
+			p = strstr(msgbuf.buf, "\n\n");
+			if (!p)
+				strbuf_addch(&msgbuf, '\n');
+
 			strbuf_addstr(&msgbuf, "(cherry picked from commit ");
 			strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
 			strbuf_addstr(&msgbuf, ")\n");
diff --git a/t/t3501-revert-cherry-pick.sh b/t/t3501-revert-cherry-pick.sh
index 6f489e2..858c744 100755
--- a/t/t3501-revert-cherry-pick.sh
+++ b/t/t3501-revert-cherry-pick.sh
@@ -70,6 +70,14 @@ test_expect_success 'cherry-pick after renaming branch' '
 
 '
 
+test_expect_success 'cherry-pick -x of one-liner commit message' '
+
+	git checkout rename2 &&
+	git cherry-pick -x added &&
+	git show -s --pretty=format:%s | test_must_fail grep "cherry picked"
+
+'
+
 test_expect_success 'revert after renaming branch' '
 
 	git checkout rename1 &&
-- 
1.8.1.4