VPP-1508 python3 tests: python3 repr.

Use six.reprlib.  Uses repr for python 2 and reprlib for python 3.

Change-Id: Ia343a492d533bd511ed57166381e10a37e452d36
Signed-off-by: Paul Vinciguerra <pvinci@vinciconsulting.com>

test/vpp_interface.py

@@ -1,5 +1,7 @@
-from abc import abstractmethod, ABCMeta
 import socket
+from abc import abstractmethod, ABCMeta
+
+import six
 
 from util import Host, mk_ll_addr, mactobinary
 
@@ -238,7 +240,7 @@ class VppInterface(object):
             raise Exception(
                 "Could not find interface with sw_if_index %d "
                 "in interface dump %s" %
-                (self.sw_if_index, repr(r)))
+                (self.sw_if_index, six.reprlib(r)))
         self._local_ip6_ll = mk_ll_addr(self.local_mac)
         self._local_ip6n_ll = socket.inet_pton(socket.AF_INET6,
                                                self.local_ip6_ll)