forever, cannot be killed
mysql_rm_table_no_locks() does TDC_RT_REMOVE_ALL which waits while
share is closed. The table normally is open only as OPEN_STUB, this is
what parser does for CREATE TABLE. But for SELECT the table is opened
not as a stub. If it is the same table name we anyway have two
TABLE_LIST objects: stub and not stub. So for "not stub"
TDC_RT_REMOVE_ALL sees open count and decides to wait until it is
closed. And it hangs because that was opened in the same thread.
The fix disables subqueries in CHECK expression at parser
level. Thanks to Sergei Golubchik <serg@mariadb.org> for the patch.
