Eliminate crash in isasl.c
Eliminate crash in isasl.c

cloudrain21/memcached-1,abhinavdangeti/memcached,cloudrain21/memcached-1,owendCB/memcached,jimwwalker/memcached,owendCB/memcached,abhinavdangeti/memcached,zbase/memcached,Metaswitch/memcached,zbase/memcached,owendCB/memcached,mrkwse/memcached,jimwwalker/memcached,couchbase/memcached,couchbase/memcached,abhinavdangeti/memcached,Metaswitch/memcached,couchbase/memcached,Metaswitch/memcached,abhinavdangeti/memcached,daverigby/memcached,jimwwalker/memcached,Metaswitch/memcached,mrkwse/memcached,zbase/memcached,mrkwse/memcached,daverigby/kv_engine,daverigby/kv_engine,daverigby/kv_engine,daverigby/memcached,zbase/memcached,daverigby/memcached,abhinavdangeti/memcached,zbase/memcached,cloudrain21/memcached-1,cloudrain21/memcached-1,daverigby/kv_engine,owendCB/memcached,Metaswitch/memcached,daverigby/memcached,couchbase/memcached,mrkwse/memcached