RyuApp: delete a key without handlers when unregistering a handler

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>

1 files changed, 2 insertions, 0 deletions

diff --git a/ryu/base/app_manager.py b/ryu/base/app_manager.py
index bdba1ec6..971918cc 100644
--- a/ryu/base/app_manager.py
+++ b/ryu/base/app_manager.py
@@ -169,6 +169,8 @@ class RyuApp(object):
     def unregister_handler(self, ev_cls, handler):
         assert callable(handler)
         self.event_handlers[ev_cls].remove(handler)
+        if not event_handlers[ev_cls]:
+            del event_handlers[ev_cls]
 
     def register_observer(self, ev_cls, name, states=None):
         states = states or set()