Use new tbl indexes to create delete trigger.

t/pt-online-schema-change/samples/del-trg-bug-1062324.sql

@@ -0,0 +1,24 @@
+drop database if exists test;
+create database test;
+use test;
+
+CREATE TABLE `t1` (
+  `c1` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
+  `c2` bigint(20) unsigned DEFAULT NULL,
+  `c3` binary(20) DEFAULT NULL,
+  PRIMARY KEY (`c1`),
+  UNIQUE KEY `2bpk` (`c2`,`c3`),
+  KEY `c3` (`c3`)
+) ENGINE=InnoDB;
+
+INSERT INTO t1 VALUES
+  (null, 1, 1),
+  (null, 1, 2),
+  (null, 1, 3),
+  (null, 1, 4),
+  (null, 1, 5),
+  (null, 2, 1),
+  (null, 2, 2),
+  (null, 2, 3),
+  (null, 2, 4),
+  (null, 2, 5);