Comment 85 for bug 190848

(In reply to comment #4)
> (In reply to comment #2)
> > qual="all" can actually already be used to test that a value is not set because
> > it always returns true when there are no values to test. i.e. All zero values
> > match.
>
> Hmm, that sounds like a bug though.

Adding "set" and "not_set" comparisons sounds sensible to make things clearer,
but I don't think the "all" behavior is a bug.

Please don't change the behavior of all.
It is this behavior that makes all,not_eq the complement of any,eq.