Custom Fields no longer get properly returned (4.5.4) when requested through the API

When I create a query like this:
/sites/all/modules/civicrm/extern/rest.php?entity=Contact&action=get&json={"sequential":1,"return":"custom_4","options":{"limit":25}}&api_key=yoursitekey&key=yourkey

I get the proper value for custom_4 in my contact

"contact_id": "25",
"contact_is_deleted": "0",
"civicrm_value_soft_credits_2_id": "6",
"custom_4": "17",
"id": "25"

However when I do this:
/sites/all/modules/civicrm/extern/rest.php?entity=Contact&action=get&json={"sequential":1,"return":"custom_4,nick_name","options":{"limit":25}}&api_key=yoursitekey&key=yourkey

"contact_id": "25",
"nick_name": "<DELETED>",
"contact_is_deleted": "0",
"civicrm_value_soft_credits_2_id": "",
"custom_4": "",
"id": "25"

This is the query:
SELECT contact_a.id as contact_id, contact_a.is_deleted as `contact_is_deleted`, contact_a.nick_name as `nick_name`, civicrm_value_soft_credits_2.id as civicrm_value_soft_credits_2_id, civicrm_value_soft_credits_2.rbucks_4 as custom_4 FROM civicrm_contact contact_a
LEFT JOIN civicrm_value_soft_credits_2 ON civicrm_value_soft_credits_2.entity_id = `contact_a`.id WHERE ( contact_a.is_deleted = '0' ) AND ( 1 ) AND ( 1 ) GROUP BY contact_a.id LIMIT 0, 25

Which when I run it manually does return NULL's for all the custom values

I think the problem sits in the "GROUP BY contact_a.id". When I either do GROUP BY contact_a.id, contact_a.nick_name" or "ORDER BY contact_a.id", it returns correctly. I think the problem is using a GROUP BY statement to order a result, however trudging through the code, I could not get heads or tails on the entire Contact/BAO/Query.php file.