LP:928352 - problems in range_vs_index_merge_innodb.test

1. run the test. mysqld.1.err will contain

120207 17:27:10 [Note] Use_count: Wrong count for key at 0x3400688, 0 should be 1
120207 17:27:10 [Note] Use_count: Wrong count for key at 0x3400688, 0 should be 1
120207 17:27:10 [Note] Use_count: Wrong count for key at 0x3400688, 0 should be 1
120207 17:27:10 [Note] Use_count: Wrong count for key at 0x3400688, 0 should be 1

2. in storage/innodb_plugin/handler/ha_innodb.cc, records_in_range() method starts from

DBUG_ASSERT(min_key || max_key);

add the same assert to xtradb. run the test. the assert will fire.