Server crash seen during savepoint release

#11 __assert_fail_base (fmt="%s%s%s:%u: %s%sAssertion `%s' failed.\n%n", 

    assertion=assertion@entry="sp && savepoint_next && *sp && *sp <= savepoint_level", 

    file=file@entry="/home/ppandith/wl-24813/storage/federatedx/federatedx_txn.cc", line=line@entry=343, 

    function=function@entry="int federatedx_txn::sp_release(ulong*)") at ./assert/assert.c:96

#12 __assert_fail (assertion="sp && savepoint_next && *sp && *sp <= savepoint_level", 

    file="/home/ppandith/wl-24813/storage/federatedx/federatedx_txn.cc", line=343, function="int federatedx_txn::sp_release(ulong*)")

    at ./assert/assert.c:105

#13 federatedx_txn::sp_release (this=, sp=) at /home/ppandith/wl-24813/storage/federatedx/federatedx_txn.cc:343

#14 ha_federatedx::savepoint_release (thd=, sv=) at /home/ppandith/wl-24813/storage/federatedx/ha_federatedx.cc:3600

#15 ha_release_savepoint (thd=, sv=) at /home/ppandith/wl-24813/sql/handler.cc:3434

#16 trans_release_savepoint (thd=, name=...) at /home/ppandith/wl-24813/sql/transaction.cc:812

#17 mysql_execute_command (thd=, is_called_from_prepared_stmt=false) at /home/ppandith/wl-24813/sql/sql_parse.cc:5628

#18 mysql_parse (thd=, rawbuf="RELEASE SAVEPOINT sp1", length=21, parser_state=) at /home/ppandith/wl-24813/sql/sql_parse.cc:7945

#19 dispatch_command (command=COM_QUERY, thd=, packet="RELEASE SAVEPOINT sp1", packet_length=21, blocking=true)

    at /home/ppandith/wl-24813/sql/sql_parse.cc:1903

#20 do_command (thd=, blocking=true) at /home/ppandith/wl-24813/sql/sql_parse.cc:1437

#21 do_handle_one_connection (connect=, put_in_cache=true) at /home/ppandith/wl-24813/sql/sql_connect.cc:1503

#22 handle_one_connection (arg=) at /home/ppandith/wl-24813/sql/sql_connect.cc:1415

#23 pfs_spawn_thread (arg=) at /home/ppandith/wl-24813/storage/perfschema/pfs.cc:2198

#24 start_thread (arg=<optimized out>) at ./nptl/pthread_create.c:447

#25 clone3 () at ../sysdeps/unix/sysv/linux/x86_64/clone3.S:78

create table s1( a int);

create table s1(a int)  ENGINE="FEDERATED" CONNECTION='mysql://u3:pass1@127.0.0.1:3306/m8/s1';

UPDATE s1 JOIN s1 AS OUTR2 SET OUTR2.a = 1 ;

BEGIN ;  

UPDATE s1 JOIN s1 AS OUTR2 SET OUTR2.a = 1 ;

SAVEPOINT sp1 ;  

RELEASE SAVEPOINT sp1 ;