Fix coverage

cliquet/storage/postgresql/client.py

@@ -83,7 +83,7 @@ def create_from_config(config, prefix=''):
     # XXX: Disable pooling at least during tests to avoid stalled tests.
     pypy_on_travis = (platform.python_implementation().lower() == 'pypy' and
                       os.getenv('TRAVIS', False))
-    if pypy_on_travis:
+    if pypy_on_travis:  # pragma: no cover
         warnings.warn('Disable pooling with PyPy on TravisCI')
         settings = dict([(poolclass_key, sqlalchemy.pool.StaticPool)])