Crash in Avro router.

Crash in the Avrorouter:

> 2019-10-22 19:03:59 notice : [CDC] avro-router: new connection from [::ffff:192.168.202.200]
> 2019-10-22 19:03:59 error : (81) [CDCPlainAuth] Authentication failed, client authentication packet length exceeds the maximum allowed length of 128 bytes.
> 2019-10-22 19:03:59 error : (81) [CDC] avro-router: authentication failure from [::ffff:192.168.202.200], user []
> 2019-10-22 19:03:59 notice : [CDC] avro-router: new connection from [::ffff:192.168.202.200]
> 2019-10-22 19:03:59 error : (82) [CDCPlainAuth] Authentication failed, client authentication packet length exceeds the maximum allowed length of 128 bytes.
> 2019-10-22 19:03:59 error : (82) [CDC] avro-router: authentication failure from [::ffff:192.168.202.200], user []
> 2019-10-22 19:03:59 notice : [CDC] avro-router: new connection from [::ffff:192.168.202.200]
> 2019-10-22 19:03:59 error : (83) [CDCPlainAuth] Authentication failed, client authentication packet length exceeds the maximum allowed length of 128 bytes.
> 2019-10-22 19:03:59 error : (83) [CDC] avro-router: authentication failure from [::ffff:192.168.202.200], user []
> 2019-10-22 19:04:00 notice : [CDC] avro-router: new connection from [::ffff:192.168.202.200]
> 2019-10-22 19:04:00 error : (84) [CDCPlainAuth] Authentication failed, the decoded client authentication packet is malformed. Expected <username>:SHA1(<password>)
> 2019-10-22 19:04:00 error : (84) [CDC] avro-router: authentication failure from [::ffff:192.168.202.200], user []
> 2019-10-22 19:04:08 notice : [CDC] avro-router: new connection from [::ffff:192.168.202.200]
> 2019-10-22 19:04:08 error : (86) [CDCPlainAuth] Authentication failed, client authentication packet length exceeds the maximum allowed length of 128 bytes.
> 2019-10-22 19:04:08 error : (86) [CDC] avro-router: authentication failure from [::ffff:192.168.202.200], user []
> 2019-10-22 19:04:08 notice : [CDC] avro-router: new connection from [::ffff:192.168.202.200]
> 2019-10-22 19:04:08 alert : Fatal: MaxScale 2.4.2 received fatal signal 11. Attempting backtrace.
> 2019-10-22 19:04:08 alert : Commit ID: aad4148d77bf2dfbaa0042bc45abda30c101cad2 System name: Linux Release string: CentOS Linux release 7.6.1810 (Core)
> 2019-10-22 19:04:09 alert : /usr/lib64/maxscale/libavro-common.so.1.0.0(_ZN11AvroSession21queue_client_callbackEv+0x1a): server/modules/routing/avrorouter/avro_client.cc:247
> 2019-10-22 19:04:09 alert : /usr/lib64/maxscale/libavro-common.so.1.0.0(_Z9notify_cbP3DCBPv+0x2b): server/modules/routing/avrorouter/avro_file.cc:384
> 2019-10-22 19:04:09 alert : /usr/lib64/maxscale/libmaxscale-common.so.1.0.0(_ZN13SerialDcbTask7executeERN7maxbase6WorkerE+0x47): server/core/dcb.cc:2543
> 2019-10-22 19:04:09 alert : /usr/lib64/maxscale/libmaxscale-common.so.1.0.0(_ZN7maxbase6Worker14handle_messageERNS_12MessageQueueERKNS_19MessageQueueMessageE+0x1d8): maxutils/maxbase/src/worker.cc:651
> 2019-10-22 19:04:09 alert : /usr/lib64/maxscale/libmaxscale-common.so.1.0.0(_ZN7maxbase12MessageQueue18handle_poll_eventsEPNS_6WorkerEj+0x138): maxutils/maxbase/src/messagequeue.cc:291
> 2019-10-22 19:04:09 alert : /usr/lib64/maxscale/libmaxscale-common.so.1.0.0(_ZN7maxbase6Worker15poll_waiteventsEv+0x196): maxutils/maxbase/src/worker.cc:858
> 2019-10-22 19:04:09 alert : /usr/lib64/maxscale/libmaxscale-common.so.1.0.0(_ZN7maxbase6Worker3runEPNS_9SemaphoreE+0x53): maxutils/maxbase/src/worker.cc:559
> 2019-10-22 19:04:10 alert : /usr/lib64/maxscale/libmaxscale-common.so.1.0.0(+0x1ad83f): thread48.o:?
> 2019-10-22 19:04:10 alert : /lib64/libpthread.so.0(+0x7dd5): pthread_create.c:?
> 2019-10-22 19:04:10 alert : /lib64/libc.so.6(clone+0x6d): ??:?