format-patch: remove a leftover debugging message

Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin-log.c

@@ -960,7 +960,6 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 	rev.boundary = 1;
 	while ((commit = get_revision(&rev)) != NULL) {
 		if (commit->object.flags & BOUNDARY) {
-			fprintf(stderr, "Boundary %s\n", sha1_to_hex(commit->object.sha1));
 			boundary_count++;
 			origin = (boundary_count == 1) ? commit : NULL;
 			continue;