Deadlocking Apache::Session::MySQL

I'm working on a combined 5.6->5.8 and MP1->MP2 migration.

I've come across a scenario where unchanged code works on 5.6/MP1 such 
that through various routes we twice tie a session object within a 
request's life.  Under the hood it seems to invoke get_lock(id) in the DB 
on when doing the tie. I'm not exeactly sure where but I assume the second 
invocation used to force, or follow,  a release_lock(str) (Also invoked 
in Apache::Session's destructor).

Within the 5.8/MP2 implementation this second invocation appears to 
dead-lock on the second tie.  One can see the get_lock waiting in the 
database and I can only image that release_lock hasn't been called for 
some reason.

Am on Apache::Session::MySQL (1.01), with differing (old and new) 
Apache::Session versions.

I am curious whether anyone has memories of seeing this before or other 
thoughts?

Thanks in advance,

Raf