civicrm_api3_basic_get does not work for SQL operators on custom fields.

If you use the api to search on a custom field of a non-contact, and you use a sql operator like <=, you get an exception. E.g.:

$result = civicrm_api3('Event', 'get', 'custom_2' => array('<=' => 'BBBB'));

Results in an exception, that contains a query like this:

Failure in api call for event get: DB Error: no such field
SELECT (lots of fields I left out), civicrm_value_testeventgetc_1.testeventgetcustomfieldlte_1 as custom_1
FROM civicrm_event a
LEFT OUTER JOIN civicrm_value_testeventgetc_1 ON civicrm_value_testeventgetc_1.entity_id = a.id
WHERE (a.testeventgetcustomfieldlte_1 <= "BBBB")
LIMIT 25
OFFSET 0

The error is in the where clause. testeventgetcustomfieldlte_1 is a field of custom_1, not a field of a.