connections
The problem is that tables can enter open table cache for a thread without 
being properly cleaned up. This can happen if make_join_statistics() fails 
to read a const table because of e.g. a deadlock. It does set a member of 
TABLE structure to a value it allocates, but doesn't clean-up this setting 
on error nor does it set the rest of the members in JOIN to allow for 
automatic cleanup.
As a result when such an error occurs and the next statement depends re-uses 
the table from the open tables cache it will get it with this 
TABLE::reginfo.join_tab pointing to a memory area that's freed.
Fixed by making sure make_join_statistics() cleans up TABLE::reginfo.join_tab 
on error.

mysql-test/r/innodb_mysql.result:
  Bug #42419: test case
mysql-test/t/innodb_mysql-master.opt:
  Bug #42419: increase the timeout so it covers te conservative 
  sleep 3 in the test
mysql-test/t/innodb_mysql.test:
  Bug #42419: test case
sql/sql_select.cc:
  Bug #42419: clean up the members of TABLE on failure in 
          make_join_statisitcs()