Problem: the table's INDEX and DATA DIR was taken
  directly from the table's first partition.
  This allowed rename attack similar to
  bug#32111 when ALTER TABLE REMOVE PARTITIONING

Solution: Silently ignore the INDEX/DATA DIR
  for the table. (Like some other storage engines
  do). 
  Partitioned tables do not support DATA/INDEX
  DIR on the table level, only on its partitions.


mysql-test/r/partition_mgm.result:
  Bug#32091: Security breach via directory changes
  test result
mysql-test/t/partition_mgm.test:
  Bug#32091: Security breach via directory changes
  test case
sql/ha_partition.cc:
  Bug#32091: Security breach via directory changes
  
  Do not use the first partition's DATA/INDEX DIR
  as the table's DATA/INDEX DIR.
  (A partitioned table do not have support for DATA/
  INDEX DIR, only its partitions do)