Removed pool_size from connect, minor tidyup

mongoengine/document.py

@@ -78,9 +78,9 @@ class Document(BaseDocument):
                 object_id = collection.save(doc, safe=safe)
         except pymongo.errors.OperationFailure, err:
             message = 'Could not save document (%s)'
-            if u'duplicate key' in err.message:
+            if u'duplicate key' in unicode(err):
                 message = u'Tried to save duplicate unique keys (%s)'
-            raise OperationError(message % err.message)
+            raise OperationError(message % unicode(err))
         id_field = self._meta['id_field']
         self[id_field] = self._fields[id_field].to_python(object_id)
 
@@ -95,7 +95,8 @@ class Document(BaseDocument):
         try:
             self.__class__.objects(**{id_field: object_id}).delete(safe=safe)
         except pymongo.errors.OperationFailure, err:
-            raise OperationError(u'Could not delete document (%s)' % err.message)
+            message = u'Could not delete document (%s)' % err.message
+            raise OperationError(message)
 
     def reload(self):
         """Reloads all attributes from the database.