Fix for bug#15336 Partitions: crash if create table as select

  added HA_EXTRA_WRITE_CACHE case to ha_partition::extra()

mysql-test/r/partition.result

@@ -562,4 +562,6 @@ partition by list (case when s1 > 'cz' then 1 else 2 end)
 (partition p1 values in (1),
 partition p2 values in (2));
 drop table t1;
+create table t1 (f1 int) partition by hash (f1) as select 1;
+drop table t1;
 End of 5.1 tests

mysql-test/t/partition.test

@@ -723,4 +723,10 @@ partition by list (case when s1 > 'cz' then 1 else 2 end)
  partition p2 values in (2));
 drop table t1;
 
+#
+# Bug#15336 Partitions: crash if create table as select
+#
+create table t1 (f1 int) partition by hash (f1) as select 1;
+drop table t1;
+
 --echo End of 5.1 tests

sql/ha_partition.cc

@@ -4703,6 +4703,7 @@ int ha_partition::extra(enum ha_extra_function operation)
     break;
   }
   case HA_EXTRA_NO_CACHE:
+  case HA_EXTRA_WRITE_CACHE:
   {
     m_extra_cache= FALSE;
     m_extra_cache_size= 0;