I've got the same problem. I downloaded the latest PHPMyAdmin and that now works, but $QUERY_STRING hold anything.
When I do login.php?Login
phpinfo() says QUERY_STRING is Login
$QUERY_STRING is blank
getenv("QUERY_STRING") is Login
However, when I say:-
$cmd = getenv getenv("QUERY_STRING")
Then print $cmd ... it says Login
But when I close the ?> php tags and open new opens and then print $cmd ... it is blank.