user.js is ignored after Tor (part) starts

Steps to reproduce:

create file Browser/TorBrowser/Data/Browser/profile.default/user.js with contents:

// blank 1st line user_pref("javascript.enabled", false); user_pref("app.update.auto", false);

Start Tor and wait for Tor connection pop up.

Make sure user.js was included: $ grep -e app.update.auto -e javascript.enabled Browser/TorBrowser/Data/Browser/profile.default/prefs.js user_pref("app.update.auto", false); user_pref("javascript.enabled", false);

Click "Connect" to and wait for browser to start

Check prefs.js again, and javascript.enabled is gone $ grep -e app.update.auto -e javascript.enabled Browser/TorBrowser/Data/Browser/profile.default/prefs.js user_pref("app.update.auto", false);

Expected behaviour: According to Firefox documentation user.js may override any preference. There's a warning that plugins that ignore this won't pass certification. After Tor has finished playing with the configuration it must apply the user.js again. With the current setup there doesn't seem to be a way to start the Tor browser with javascript.enabled set to false and allow the user to change it to true if that want.

Background: We are running Tor inside docker, so constantly downloading updates until we can update the docker image seems like unnecessary waste of precious onion bandwidth.

With app.update.auto set to false, we get a pop up which says there is a new version available so we can update in our own time.

With the current setup there doesn't seem to be a way to start the Tor browser with javascript.enabled set to false and allow the user to change it to true if that want.

Trac:
Username: davidnewcomb