Fix typo (signal instead of signal_).

ccnode/node.py

@@ -188,9 +188,9 @@ class MainLoop(object):
 
         # turn into real watchers
         self.signals = dict((
-            signal,
-            self.evloop.signal(signal, cb),
-        ) for signal, cb in self.signals.iteritems())
+            signal_,
+            self.evloop.signal(signal_, cb),
+        ) for signal_, cb in self.signals.iteritems())
 
         # load config variables
         self.config = NodeConfigParser(self.config_path)