translation.module: query filtering non existing NULL values instead of 0

looking at the definition of table i18n_node

mysql> describe i18n_node;
+----------+------------------+------+-----+---------+-------+
| Field    | Type             | Null | Key | Default | Extra |
+----------+------------------+------+-----+---------+-------+
| nid      | int(11) unsigned | NO   | PRI |         |       |
| trid     | int(10) unsigned | NO   |     | 0       |       |
| language | varchar(12)      | NO   |     |         |       |
| status   | smallint(6)      | NO   |     | 0       |       |
+----------+------------------+------+-----+---------+-------+

it is obvious that there can't be NULL values in column trid. But the default is 0.
The attached patch corrects this in function translation_node_nid. Otherwise the first value of the result set is returned pointing to some random node.