Add failing test case.

t/pt-online-schema-change/samples/data-loss-bug-1068562.sql

@@ -0,0 +1,11 @@
+drop database if exists bug1068562;
+create database bug1068562;
+use bug1068562;
+
+CREATE TABLE `simon` (
+  `id` int(11) NOT NULL,
+  `old_column_name` varchar(255) DEFAULT NULL,
+  PRIMARY KEY (`id`)
+) ENGINE=InnoDB;
+
+insert into simon values (1,'a'),(2,'b'),(3,'c');