Private browsing mode should be disabled in TBB
Firefox private browsing mode currently prevents the user from setting various Torbutton options related to disk storage.
Right now private browsing mode also provides no benefit over default Torbutton settings. Furthermore, it will be relatively easy to take any useful future private browsing mode features we need on a piecemeal basis for the medium term future.
Long term, we've suggested to Mozilla that they provide private browsing mode options that are more compatible with how we want to do things (#3100 (closed)). If/when this happens, we'll map our options to private browsing mode options.