In bug 1542244 the file testing/marionette/prefs/marionette.js got two new additions:
+// Turn off DOM Push
+// Privacy and tracking protection
Despite the path, these preferences ship as part of the default Firefox preferences.
To prevent from accidentally shipping such changes, automatically forbidding them would be helpful, e.g. allow that file to only set
Would be storing the whitelisted branches at the top of the file, reading them and checking no
pref( call starts with anything else be the way to go (in a Makefile)?