decide if we need a watershed update prior to our esr78-based Tor Browser
Firefox 72.0.2 was a watershed release: all users of older versions are first updated to 72.0.2 before getting an update to the current release. Why? Because Mozilla removed the code that knew how to migrate from key3.db to key4.db. Should we force all Tor Browser users to update to our last esr68-based Tor Browser so they have key4.db the first time they run an esr78-based Tor Browser? I am not 100% sure, but I think key3.db was only used for storing passwords (and maybe only the master NSS password?)