SASL minimum layer used to work at 256, but now requires 1

[Stephen Ingram]

I recently upgraded a CentOS 7 Cyrus 2.4.17 system with Murder and Kerberos
and ran into lots of issues with the new packages. What's really puzzling
though is although I used to be able to use a SASL minimum layer of 256
(I'm using TLS with GSSAPI for auth), I now must use 1 for the front-ends
and backends communicating to the mupdate server. I've run into SASL
package issues before (2.1.23 to 2.1.26 was a mess) and had to actually
revert to an older version so I'm thinking that might be the problem.
However, when I use mupdatetest and imtest, everything works perfectly.
It's only when I fire up the daemons themselves that I see:

Jun 1 23:53:21 imap mupdate[19865]: couldn't authenticate to backend
server: mechanism too weak for this user
Jun 1 23:53:21 imap mupdate[19865]: mupdate_connect failed: no auth status
Jun 1 23:53:21 imap mupdate[19865]: couldn't connect to mupdate server
Jun 1 23:53:21 imap mupdate[19865]: retrying connection to mupdate server
in 27 seconds

If I grab a ticket and mupdatetest -m GSSAPI -t '' mupdate.test.net with a
256 min layer, I get in perfectly. So perhaps it's a change/new config
issue in cyrus-imap this time around?

I'm using cyrus-imapd-2.4.17-13 and cyrus-sasl-2.1.26-23 versions of the
various package sets.

Steve