Okay, let KeyboardInterrupt through

src/allmydata/test/test_observer.py

@@ -141,3 +141,16 @@ class Observer(unittest.TestCase):
 
         self.assertEqual([None], observed)
         self.assertEqual(1, len(self.flushLoggedErrors(Exception)))
+
+    def test_observer_list_propagate_keyboardinterrupt(self):
+        """
+        ``KeyboardInterrupt`` escapes ``ObserverList.notify``.
+        """
+        def observer_one():
+            raise KeyboardInterrupt()
+
+        obs = observer.ObserverList()
+        obs.subscribe(observer_one)
+
+        with self.assertRaises(KeyboardInterrupt):
+            obs.notify()

src/allmydata/util/observer.py

@@ -118,7 +118,7 @@ class ObserverList(object):
         for o in self._watchers[:]:
             try:
                 o(*args, **kwargs)
-            except:
+            except Exception:
                 self._logger.failure("While notifying {o!r}", o=o)
 
 class EventStreamObserver(object):