Stoopid import was still hanging around.

moto/events/models.py

@@ -1,6 +1,5 @@
 import os
 import re
-from collections import OrderedDict
 
 from moto.core import BaseBackend
 

moto/events/urls.py

@@ -8,4 +8,4 @@ url_bases = [
 
 url_paths = {
     "{0}/": EventsHandler.dispatch,
-}
+}