Do a little experiment:

1) Set Bugzilla_login to ayn2
2) Set Bugzilla_logincookie to something invalid (like 0). Now go to
query.cgi

BAD things happen:

1) All my saved queries are available (security issue!).
2) It does not suggest to log in at the top of the page (which it does when
Bugzilla_login is not set).
3) It does not give option to log out and log in as somebody else at the
bottom of the page (which it does when it thinks I am logged in).