When requesting an $urlget() with the 'bh' (binvar; HEAD) options, there is no target binvar created within the callback alias, as there is with 'bg' (binvar; GET).
This seems invalid, because $urlget(%id).target will declare a &binvar name, but that binvar does not exist. It causes $bvar(&binvar,1-).text to throw an erroneous error.
I'm of the opinion that the &target binvar should be populated by the header reply when requesting the HEAD method.
