PT-157 Specifying the index to use for pt-archiver ignores --primary-key-only

t/pt-archiver/samples/pt_157.sql

@@ -0,0 +1,20 @@
+DROP DATABASE IF EXISTS test;
+CREATE DATABASE test;
+
+CREATE TABLE `test`.`t1` (
+  f1 INT NOT NULL,
+  f2 VARCHAR(10)
+) Engine=InnoDB;
+
+INSERT INTO `test`.`t1` VALUES
+(1, 'a'),
+(2, 'b'),
+(3, 'c'),
+(4, 'd'),
+(5, 'e'),
+(6, 'f'),
+(7, 'g'),
+(8, 'h'),
+(9, 'i'),
+(10, 'j');
+