Fix files after pep8 check

Related-Prod: PROD-36999

Change-Id: Ie6d952aa97545873089478339080931720569dba
diff --git a/tcp_tests/helpers/containers.py b/tcp_tests/helpers/containers.py
index 7d1306a..f7f78af 100644
--- a/tcp_tests/helpers/containers.py
+++ b/tcp_tests/helpers/containers.py
@@ -148,7 +148,7 @@
              "failed: {1}.").format(self.image_name, result)
         result = self.remote.execute(check_alias_cmd)
         assert result['exit_code'] == 0, \
-            ("Alias creation for running {} from container "
+            ("Alias creation for running {0} from container "
              "failed: {1}.").format(self.image_name, result)
 
     def setup(self):