Comment # 1 on bug 968843 from Ryan Wilson

I can tell you exactly why the error would have happened, but I've been unable
to replicate the issue.

The 'GoAheadAndLogIn=1' is a parameter that confirms login if already logged
in, or redirects to the login page if you are not. Parameter logic for all URLs
(not just Bugzilla) requires the first parameter to be preceded by a '?', while
all subsequent parameters are preceded by '&'. Because of this, the '?'
preceding GoAheadAndLogIn is read as an actual question mark, creating the
incorrect parameter 'allwordssubtr?GoAheadAndLogIn'. The URL would be properly
formed if changed to an '&'.

Unless you are able to replicate this again and provide step-by-step
instructions on how to recreate, I will have to mark this bug as WORKSFORME.