Changing the IP table for an interface is an error if the interface already has an address configured (VPP-601)

Change-Id: I311fc264f73dd3b2b3ce9d7d1c33cd0515b36c4a
Signed-off-by: Neale Ranns <nranns@cisco.com>
diff --git a/test/test_mpls.py b/test/test_mpls.py
index 41d9426..9082637 100644
--- a/test/test_mpls.py
+++ b/test/test_mpls.py
@@ -17,10 +17,6 @@
 class TestMPLS(VppTestCase):
     """ MPLS Test Case """
 
-    @classmethod
-    def setUpClass(cls):
-        super(TestMPLS, cls).setUpClass()
-
     def setUp(self):
         super(TestMPLS, self).setUp()
 
@@ -44,6 +40,11 @@
 
     def tearDown(self):
         super(TestMPLS, self).tearDown()
+        for i in self.pg_interfaces:
+            i.unconfig_ip4()
+            i.unconfig_ip6()
+            i.ip6_disable()
+            i.admin_down()
 
     # the default of 64 matches the IP packet TTL default
     def create_stream_labelled_ip4(