trac guest account doesn't work

The bug reporting instructions at https://ghc.haskell.org/trac/ghc/wiki/ReportABug say

To submit an anonymous bug: use login "guest", password "guest"

Doing so just results in

Error

Invalid username or password

Trac metadata

Trac field	Value
Version	8.0.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Trac & Git
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture