mysql-test/r/heap_hash.result:
  Testcase for BUG#8371: wrong rec_per_key value for hash index on temporary table
mysql-test/t/heap_hash.test:
  Testcase for BUG#8371: wrong rec_per_key value for hash index on temporary table
sql/ha_heap.cc:
  Fix for BUG#8371: wrong rec_per_key value for hash index on temporary table:
  Don't assume that table->rec_per_key==NULL if table->tmp_table != NO_TMP_TABLE, 
  this is not true for tables created with "CREATE TEMPORARY TABLE" (while it holds
  for temporary tables created during query execution)
sql/sql_select.cc:
  Initialize rec_per_key for all keys in temporary table.