crm_get_contact() fails to find organization if email specified

Using CiviCRM version 1.7.9379:

crm_get_contact( $params ) doesn't find a contact, but crm_create_contact(
$params ) does, using $params such as this:

$params = array(3)

{ ["contact_type"]=> string(12) "Organization" ["organization_name"]=> string(20) "Dark City Coffee Co." ["email"]=> string(26) "raymond@darkcitycoffee.com" }

Removing the 'email' element lets it work as expected.