Call to docker-py changed upstream

test/600_proxy_docker_py_test.sh

@@ -13,7 +13,7 @@ if docker_on $HOST1 run \
     -e DOCKER_HOST=tcp://172.17.42.1:12375 \
     -v /tmp:/tmp \
     -v /var/run/docker.sock:/var/run/docker.sock \
-    joffrey/docker-py python tests/integration_test.py ; then
+    joffrey/docker-py py.test tests/integration_test.py ; then
     assert_raises "true"
 else
     assert_raises "false"