do not fail on checking for submitter when user hashes get disabled

wcs/formdata.py

@@ -314,8 +314,11 @@ class FormData(StorableObject):
     def is_submitter(self, user):
         if self.user_id and str(self.user_id) == str(user.id):
             return True
-        if self.user_hash and self.user_hash == user.hash:
-            return True
+        try:
+            if self.user_hash and self.user_hash == user.hash:
+                return True
+        except AttributeError:
+            return False
         return False
 
     # don't pickle _formdef cache