Comment 9 for bug 1791789

Our custom search engines reappearing between search engine cache rebuilds is not a new issue, but it's being made worse by a new bug (https://bugzilla.mozilla.org/show_bug.cgi?id=1489820) which is causing a cache rebuild to happen on every restart rather than after app upgrades (and is also responsible for making some en-US search engines appear for non en-US users).

I've found some other issues with our search defaults as well. I'll have some updates for this tomorrow.