revert: fix off by one read when searching the end of a commit subject

A test case is added but the problem can only be seen when running
the test case with --valgrind.

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Acked-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/revert.c

@@ -127,7 +127,7 @@ static int get_message(const char *raw_message, struct commit_message *out)
 		p++;
 	if (*p) {
 		p += 2;
-		for (eol = p + 1; *eol && *eol != '\n'; eol++)
+		for (eol = p; *eol && *eol != '\n'; eol++)
 			; /* do nothing */
 	} else
 		eol = p;

t/t3505-cherry-pick-empty.sh

@@ -13,11 +13,29 @@ test_expect_success setup '
 
 	git checkout -b empty-branch &&
 	test_tick &&
-	git commit --allow-empty -m "empty"
+	git commit --allow-empty -m "empty" &&
+
+	echo third >> file1 &&
+	git add file1 &&
+	test_tick &&
+	git commit --allow-empty-message -m ""
 
 '
 
 test_expect_success 'cherry-pick an empty commit' '
+	git checkout master && {
+		git cherry-pick empty-branch^
+		test "$?" = 1
+	}
+'
+
+test_expect_success 'index lockfile was removed' '
+
+	test ! -f .git/index.lock
+
+'
+
+test_expect_success 'cherry-pick a commit with an empty message' '
 	git checkout master && {
 		git cherry-pick empty-branch
 		test "$?" = 1