test failure: index_merge_myisam

cmake /source -DCMAKE_BUILD_TYPE=Debug -DWITH_PROTOBUF=system -DWITH_NDB_JAVA=NO -DCMAKE_C_COMPILER=/opt/at10.0/bin/gcc -DCMAKE_CXX_COMPILER=/opt/at10.0/bin/g++ '-DCMAKE_C_FLAGS_RELWITHDEBINFO=-m64 -O3 -g -mtune=native' '-DCMAKE_CXX_FLAGS_RELWITHDEBINFO=-m64 -O3 -g -mtune=native' '-DCMAKE_C_FLAGS=-m64 -O3 -g -mtune=native' '-DCMAKE_CXX_FLAGS=-m64 -O3 -g -mtune=native' -DWITH_SSL=system -DCMAKE_INSTALL_PREFIX=/mysql/mariadb-upstream-Debug-10.0 -DCMAKE_AR=/opt/at10.0/bin/ar -DCMAKE_C_COMPILER_LAUNCHER=ccache -DCMAKE_CXX_COMPILER_LAUNCHER=ccache -DWITHOUT_FEDERATED_STORAGE_ENGINE=1 -DWITHOUT_FEDERATEDX_STORAGE_ENGINE=1 -DWITHOUT_TOKUDB_STORAGE_ENGINE=1

...

./mtr '--skip-test='\''gis.(geometry_property_function_issimple|gis_bugs_crashes|spatial_utility_function_simplify|spatial_analysis_functions_buffer|spatial_op_testingfunc_mix)'\''' --skip-test=parts.partition_alter2_1_myisam '--skip-test='\''tokudb_parts.*'\''' --skip-test=connect.tbl --skip-test=rpl.rpl_parallel --skip-test=encryption.innodb_encryption-page-compression --skip-test=perfschema.socket_summary_by_event_name_func '--skip-test='\''main.mysql_client_test.*'\''' --skip-test=spider/bg.spider_fixes '--skip-test='\''encryption.create_or_replace.*'\''' '--skip-test='\''wsrep_info.plugin.*'\''' --skip-test=rpl.rpl_semi_sync --skip-test=binlog_encryption.rpl_semi_sync --skip-test=encryption.innodb-encryption-disable --skip-test=encryption.innodb_onlinealter_encryption '--skip-test='\''binlog_encryption.*'\''' --force --big-test --nowarnings

...

...

07:14:41 ];mtr: spent 0:02:47 on 3654 tests. 0:01:03 (1389 tests) leftmain.index_merge_myisam                  w79 [ fail ]

07:14:41         Test ended at 2017-04-09 21:14:41

07:14:41 

07:14:41 CURRENT_TEST: main.index_merge_myisam

07:14:41 --- /source/mysql-test/r/index_merge_myisam.result	2017-04-09 21:09:22.015154733 +0000

07:14:41 +++ /source/mysql-test/r/index_merge_myisam.reject	2017-04-09 21:14:41.159782263 +0000

07:14:41 @@ -521,8 +521,11 @@

07:14:41  4	5	0

07:14:41  4	filler	4

07:14:41  4	filler	4

07:14:41 +4	filler	4

07:14:41 +4	filler	4

07:14:41  4	qq	5

07:14:41  4	zz	4

07:14:41 +4	zz	4

07:14:41  5	qq	4

07:14:41  drop table t1, t2;

07:14:41  CREATE TABLE t1 (a varchar(8), b set('a','b','c','d','e','f','g','h'),

07:14:41 

07:14:41 mysqltest: Result length mismatch