Two bug fixes related to mirroring:

- default_hostgroup was not set: this causes multiplexing to always be disabled
- fd in client_myds for mirror session was not initialized: this causes random crashes

lib/MySQL_Session.cpp

@@ -649,6 +649,7 @@ void MySQL_Session::handler___status_WAITING_CLIENT_DATA___STATE_SLEEP___MYSQL_C
 		newsess->client_myds = new MySQL_Data_Stream();
 		newsess->client_myds->DSS=STATE_SLEEP;
 		newsess->client_myds->sess=newsess;
+		newsess->client_myds->fd=0;
 		newsess->client_myds->myds_type=MYDS_FRONTEND;
 		newsess->client_myds->PSarrayOUT= new PtrSizeArray();
 		newsess->thread_session_id=__sync_fetch_and_add(&glovars.thread_id,1);
@@ -659,6 +660,7 @@ void MySQL_Session::handler___status_WAITING_CLIENT_DATA___STATE_SLEEP___MYSQL_C
 		newsess->client_myds->attach_connection(myconn);
 		newsess->client_myds->myprot.init(&newsess->client_myds, newsess->client_myds->myconn->userinfo, newsess);
 		newsess->to_process=1;
+		newsess->default_hostgroup=default_hostgroup;
 		if (qpo->mirror_hostgroup>= 0) {
 			newsess->mirror_hostgroup=qpo->mirror_hostgroup; // in the new session we copy the mirror hostgroup
 		} else {