BUG using isDev query string no longer triggers basic auth (do not merge)

cc @hafriedlander

I know upgrading docs are required for this. I'll write them if you think this is a good solution and remove the do not merge.
You don't need to check if a key isset for the unset call, it won't throw a notice.

However, I think messing with the superglobal is a bit nasty, can't it be suppressed from the current SS_HTTPRequest object instead?