nova show returns wrong hypervisor_hostname

Related table info:

mysql> select id, host, disabled from services;
+----+-----------+----------+
| id | host | disabled |
+----+-----------+----------+
| 1 | ivan-dev0 | 0 |
| 2 | ivan-dev0 | 0 |
| 3 | ivan-dev0 | 0 |
| 4 | ivan-dev0 | 0 |
| 5 | ivan-dev0 | 0 |
| 6 | ivan-dev2 | 0 |
| 7 | ivan-dev2 | 1 |
| 8 | ivan-dev2 | 1 |
+----+-----------+----------+
8 rows in set (0.00 sec)

mysql> select id, hypervisor_hostname, service_id from compute_nodes;
+----+---------------------+------------+
| id | hypervisor_hostname | service_id |
+----+---------------------+------------+
| 1 | ivan-dev0 | 1 |
| 3 | ivan-dev2 | 6 |
+----+---------------------+------------+
2 rows in set (0.00 sec)

Now we try to call db.compute_node_get_by_host

compute_node = db.compute_node_get_by_host(context, 'ivan-dev2')
# expect the print below outputs "ivan-dev2"
print compute_node['hypervisor_hostname']
ivan-dev0
# but the output is "ivan-dev0"