Comment 5 for bug 1830096

This was reported as an ubuntu bug: https://bugs.launchpad.net/firefox/+bug/1830096.

It seems unfortunate that firefox uses MOZ_BUILD_DATE as its build ID (if I followed correctly the code path, see https://hg.mozilla.org/mozilla-central/file/tip/build/variables.py#l15).

The official build from Mozilla might not be affected by that bug, but on Ubuntu we build firefox for each supported release (at present that's 16.04, 18.04, 18.10, 19.04 and the development series, 19.10), which means that the same package of firefox for two different Ubuntu releases will be getting different build IDs, and there's no way to guarantee that the build ID for release X will be < the build ID for release Y, where X < Y (other than building the packages sequentially, instead of in parallel).