[Qt-interest] Comparing two NULL QVariants returns true

[Robert Hairgrove]

In the internal "compare()" function in file qvariant.cpp, the case
where two null variants are compared is at the very bottom:

    if (a->is_null && b->is_null)
        return true;

I was wondering why this is implemented as such, whereas most databases
will return false when two NULL values are compared. What was the
rationale behind this?