[horde] 'Hashtable' sessions not working with 5.1.1

[Rick Romero]

Hi guys,

I just upgraded to 5.1.1 from 5.1.0, and I was using HashTable session
management with a Memcache server on the backend.  It seems to have
stopped working - sessions no longer register, even in test.php.  And of
course, I wasn't 'authorized for horde'

I backed up to 'Builtin', and was finally able to login.  I reset the
config thinking maybe something with it changed, but reselecting Hashtable
caused sessions to break again.  I've currently set my sessionhandler to
SQL, which works fine.
So is there a problem with the Hashtable sessionhandler?  Or maybe just a
problem with Memcache and Hashtable?
I recall seeing a suggestion that redis is preferred over memcache, is
memcache support going away?

Thanks,
Rick