Comment 23 for bug 1798399

I don't know where it's written, but it does make sense. Although I think I overstated the requirement because really I can only see a justification to get all fixes into the _next_ release before backporting.

You don't want to declare a bug fixed in the latest LTS only to find months or years later that the fix is missing in newer releases. So we must ensure every fix exists in the _next_ release before it is put into any previous release.