LP:613029 - Wrong result with materialization and semijoin, and valgrind warnings in Protocol::net_store_data with materialization for implicit grouping

Queries such as

SELECT table1 .`col_varchar_nokey` , MAX( table1 .`col_int_key` )
FROM C table1 JOIN (
SELECT *
FROM B ) table2 ON table2 .`pk` = table1 .`pk`
WHERE ( table1 .`col_int_nokey` , table2 .`pk` ) IN (
SELECT `col_int_nokey` , `col_int_key`
FROM C ) ;

SELECT *
FROM (
SELECT table1 .`col_varchar_nokey` , MAX( table1 .`col_int_key` )
FROM C table1 JOIN (
SELECT *
FROM B ) table2 ON table2 .`pk` = table1 .`pk`
WHERE ( table1 .`col_int_nokey` , table2 .`pk` ) IN (
SELECT `col_int_nokey` , `col_int_key`
FROM C ) ) AS
FROM_SUBQUERY /* TRANSFORM_OUTCOME_UNORDERED_MATCH */;

cause valgrind warnings when run with semijoin=off,partial_match_rowid_merge=off. With a suitable client, one can also observe garbage data being sent to the client.