Only variables should be passed by reference in commerce_add_to_cart_extras_handler_field_quantity->views_form_submit()

Running PHP 5.5.17 I get the following strict warning:

Strict warning: Only variables should be passed by reference in commerce_add_to_cart_extras_handler_field_quantity->views_form_submit() (line 172 of docroot/sites/all/modules/contrib/commerce_add_to_cart_extras/commerce_add_to_cart_extras_handler_field_quantity.inc).

On line 172:

$path = 'node/' . array_shift(array_keys($result['node']));

The array keys must be set to variable and that variable is then passed in like so:

$array_keys = array_keys($result['node']);
$path = 'node/' . array_shift($array_keys);
unset($array_keys);