dummy: iterate over a copy of dictionary keys as they are changed in the loop

eopayment/dummy.py

@@ -111,7 +111,7 @@ class Payment(PaymentCommon):
         }
         query.update(dict(name=name, address=address, email=email, phone=phone,
             orderid=orderid, info1=info1, info2=info2, info3=info3))
-        for key in query.keys():
+        for key in list(query.keys()):
             if query[key] is None:
                 del query[key]
         url = '%s?%s' % (SERVICE_URL, urllib.urlencode(query))