I recently used Firefox Nightly on my Android device, in a private tab, to login to gmail. After I closed the browser, both via the "quit" menu icon and via swiping the Firefox away in the Overview, I had expected the session information to be deleted and the next time I came back to gmail via a private tab, to be required to login again. However, this was not the case. Despite closing out the browser, something seems to have survived and the I was immediately logged back into the gmail session.
Is this some sort of expected behavior? Shouldn't closing out the browser delete all session information from a private tab? Is there something I missed that maybe I'm not actually "closing" the browser?
That should have certainly removed the session data and therefore logged you out. While it rarely happens, it is possible that something like this is simply broken on Nightly...