test/rpc: import the errno module

Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

test/rpc/ps_test.py

 #!/usr/bin/python
 
-import socket, os, imp, sys
+import socket, os, imp, sys, errno
 import rpc_pb2 as rpc
 import argparse