Python 3 preparation: avoid assigning to instance __getitem__ in TruthDict.

In Python 3, special method names are generally only looked up at the
class level, not on instance objects, and so assigning to them for an
instance object doesn't work as expected.

Author: jsm28

roundup/support.py

@@ -15,11 +15,12 @@ def __init__(self, keys):
             self.keys = {}
             for col in keys:
                 self.keys[col] = 1
-        else:
-            self.__getitem__ = lambda name: 1
 
     def __getitem__(self, name):
-        return name in self.keys
+        if hasattr(self, 'keys'):
+            return name in self.keys
+        else:
+            return True
 
 def ensureParentsExist(dest):
     if not os.path.exists(os.path.dirname(dest)):