Fix log_console_output call in test_network_basicops

The call is currently iterating over self.servers expecting it to
return a key-value pair. That would be true for self.server.items or
self.server.iteritimes, but not self.server.

This patch just passes self.servers.keys to log_console_output

Change-Id: I8cb9e5e44ffbb7ac9308d1f3b31c76949b9ffb4f
diff --git a/tempest/scenario/test_network_basic_ops.py b/tempest/scenario/test_network_basic_ops.py
index 94e0f81..804cacd 100644
--- a/tempest/scenario/test_network_basic_ops.py
+++ b/tempest/scenario/test_network_basic_ops.py
@@ -229,8 +229,7 @@
                                                     key.private_key)
         except Exception:
             LOG.exception('Tenant connectivity check failed')
-            self._log_console_output(
-                servers=[server for server, _key in self.servers])
+            self._log_console_output(servers=self.servers.keys())
             debug.log_ip_ns()
             raise
 
@@ -268,8 +267,7 @@
                                             should_connect=should_connect)
         except Exception:
             LOG.exception('Public network connectivity check failed')
-            self._log_console_output(
-                servers=[server for server, _key in self.servers])
+            self._log_console_output(servers=self.servers.keys())
             debug.log_ip_ns()
             raise