make label_selector default empty string
@@ -52,7 +52,7 @@ def _monitor(k8s_api, namespace, container_names, label_selector, watch_ttl):
def monitor(k8s_api,
namespace,
container_names,
- label_selector=None,
+ label_selector='',
return_event=False,
watch_ttl=None,
resource_version=None,
