Merge branch 'master' into schema-alteration

1 files changed, 7 insertions, 1 deletions

diff --git a/django/utils/datastructures.py b/django/utils/datastructures.py
index ec68892870..b0b1cd6b1d 100644
--- a/django/utils/datastructures.py
+++ b/django/utils/datastructures.py
@@ -14,13 +14,19 @@ class MergeDict(object):
     def __init__(self, *dicts):
         self.dicts = dicts
 
+    def __bool__(self):
+        return any(self.dicts)
+
+    def __nonzero__(self):
+        return type(self).__bool__(self)
+
     def __getitem__(self, key):
         for dict_ in self.dicts:
             try:
                 return dict_[key]
             except KeyError:
                 pass
-        raise KeyError
+        raise KeyError(key)
 
     def __copy__(self):
         return self.__class__(*self.dicts)