Redirects sometimes seem to break circuit status UI
If you go to https://bugs.torproject.org, you will be redirected to https://trac.torproject.org, and in some cases the circuit status UI will not display a circuit for you. It seems that even subsequent visits to trac.torproject.org will not display a circuit. Others have reported similar issues with google.com country redirects.
This happens with TBB 4.5a5, but is not reliably reproducible. Sometimes the UI actually displays a circuit after the redirect.