utf8: release strbuf on error return in strbuf_utf8_replace()

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

utf8.c

@@ -381,7 +381,7 @@ void strbuf_utf8_replace(struct strbuf *sb_src, int pos, int width,
 		old = src;
 		n = utf8_width((const char**)&src, NULL);
 		if (!src) 	/* broken utf-8, do nothing */
-			return;
+			goto out;
 		if (n && w >= pos && w < pos + width) {
 			if (subst) {
 				memcpy(dst, subst, subst_len);
@@ -397,6 +397,7 @@ void strbuf_utf8_replace(struct strbuf *sb_src, int pos, int width,
 	}
 	strbuf_setlen(&sb_dst, dst - sb_dst.buf);
 	strbuf_swap(sb_src, &sb_dst);
+out:
 	strbuf_release(&sb_dst);
 }