Call by reference error

I got the following message when migrating from my local dev environment:

Warning: Call-time pass-by-reference has been deprecated; If you would like to pass it by reference, modify the declaration of [runtime function name](). If you would like to enable call-time pass-by-reference, you can set allow_call_time_pass_reference to true in your INI file in /html/sites/all/modules/conditional_fields/conditional_fields.module on line 899.

The following change removed the error, but since I'm not a coder, I have no idea what the repurcussions/signifance of the change is:

    // broken _ conditional_fields_set_required_for_render(&$item);
    conditional_fields_set_required_for_render($item); //working