Aegir 3.x does not supply an aegir_api variable

From recent installations of aegir:

mysql> select * from variable where name like '%aegir%';
+---------------------------+-----------+
| name                      | value     |
+---------------------------+-----------+
| aegir_hostmaster_site_nid | s:2:"10"; |
+---------------------------+-----------+
1 row in set (0.00 sec)

$> drush @hostmaster variable-get aegir_api --format=string
0

Work-around by setting it in local.setting.php or manually entering it in the database.