Merge branch 'cc/trailers-corner-case-fix'

"interpret-trailers" helper mistook a single-liner log message that
has a colon as the end of existing trailer.

* cc/trailers-corner-case-fix:
  trailer: retitle a test and correct an in-comment message
  trailer: ignore first line of message

t/t7513-interpret-trailers.sh

@@ -93,12 +93,25 @@ test_expect_success 'with config option on the command line' '
 		Acked-by: Johan
 		Reviewed-by: Peff
 	EOF
-	echo "Acked-by: Johan" |
+	{ echo; echo "Acked-by: Johan"; } |
 	git -c "trailer.Acked-by.ifexists=addifdifferent" interpret-trailers \
 		--trailer "Reviewed-by: Peff" --trailer "Acked-by: Johan" >actual &&
 	test_cmp expected actual
 '
 
+test_expect_success 'with only a title in the message' '
+	cat >expected <<-\EOF &&
+		area: change
+
+		Reviewed-by: Peff
+		Acked-by: Johan
+	EOF
+	echo "area: change" |
+	git interpret-trailers --trailer "Reviewed-by: Peff" \
+		--trailer "Acked-by: Johan" >actual &&
+	test_cmp expected actual
+'
+
 test_expect_success 'with config setup' '
 	git config trailer.ack.key "Acked-by: " &&
 	cat >expected <<-\EOF &&

trailer.c

@@ -740,8 +740,10 @@ static int find_trailer_start(struct strbuf **lines, int count)
 	/*
 	 * Get the start of the trailers by looking starting from the end
 	 * for a line with only spaces before lines with one separator.
+	 * The first line must not be analyzed as the others as it
+	 * should be either the message title or a blank line.
 	 */
-	for (start = count - 1; start >= 0; start--) {
+	for (start = count - 1; start >= 1; start--) {
 		if (lines[start]->buf[0] == comment_line_char)
 			continue;
 		if (contains_only_spaces(lines[start]->buf)) {