Activity history search API does not honor the 'entity_id' parameter

Drupal 4.7.1
CiviCRM rev5367M
PHP 4.4.1 (cli) (built: Mar 5 2006 10:30:50)

I am using the activity history API to search for history records for a specific user. here is the code:

--------
$params = array(
'entity_id' => $crm_user->id,
'entity_table' => 'civicrm_contact',
'module' => 'civicontact',
'activity_id' => $node->nid,
);
$params = array();
$sort = array("activity_date" => "DESC");

$activities = crm_get_activity_history($params, 0, 1, $sort);
------
Expected behavior: For users with no history items of this type, this search should return no results.

Actual Behavior: Returns an activity history for a different contact record.

For example, if I hard code the code to behave like this:

$params = array(
'entity_id' => 104,
'entity_table' => 'civicrm_contact',
'module' => 'civicontact',
'activity_id' => $node->nid,
);
$params = array();
$sort = array("activity_date" => "DESC");

$activities = crm_get_activity_history($params, 0, 1, $sort);
dprint_r($activities);

the debugging system will print out:

Array
(
[771] => Array
(
[id] => 771
[entity_table] => civicrm_contact
[entity_id] => 24
[activity_type] => Completed Campaign
[module] => civicontact
[callback] => civicontact_activity_callback
[activity_id] => 10
[activity_summary] => Completed the Candidate Survey 2006 campaign
[activity_date] => 2006-05-26 15:03:48
)

)

Note that the entity_id is totally wrong. I would guess that this parameter is just not being included in the SQL somewhere.