Fix displaying issues when the custom field list has no options
    
    Basically this has happened a few times when importing a project into
    pagure, the custom field of type list is created, given a value but no
    data field (ie: no list of options).
    This breaks the entire page since we fails at offering the different
    options for that field.
    
    With this fix, we do not fix the root cause but we do fix the symptoms.