rename: warn user when we have turned off rename detection

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diffcore-rename.c

@@ -468,10 +468,11 @@ void diffcore_rename(struct diff_options *options)
 	 */
 	if (rename_limit <= 0 || rename_limit > 32767)
 		rename_limit = 32767;
-	if (num_create > rename_limit && num_src > rename_limit)
-		goto cleanup;
-	if (num_create * num_src > rename_limit * rename_limit)
+	if ((num_create > rename_limit && num_src > rename_limit) ||
+	    (num_create * num_src > rename_limit * rename_limit)) {
+		warning("too many files, skipping inexact rename detection");
 		goto cleanup;
+	}
 
 	mx = xmalloc(sizeof(*mx) * num_create * num_src);
 	for (dst_cnt = i = 0; i < rename_dst_nr; i++) {