Fixed a bug with index inheritance.

    
Fields would seem to not obey the MRO while method did. Thanks to ironfroggy for the report!

Author: toastdriven

haystack/indexes.py

@@ -15,6 +15,8 @@ def __new__(cls, name, bases, attrs):
         # Inherit any fields from parent(s).
         try:
             parents = [b for b in bases if issubclass(b, SearchIndex)]
+            # Simulate the MRO.
+            parents.reverse()
 
             for p in parents:
                 fields = getattr(p, 'fields', None)