[arch-general] packages creating users and groups without explicit UID / GID?

[Ray Kohler]

Recently I've noticed a couple of packages (git and util-linux) that
are creating system users and groups ("git" and "uuidd") without
explicitly choosing a UID or GID. These are then assigned IDs near the
top of the SYS_UID_MAX / SYS_GID_MAX range. Previously, such
post_install scripts were hard-coding these numbers based on
https://wiki.archlinux.org/index.php/DeveloperWiki:UID_/_GID_Database
.

Is this an "official" change of direction, such that I should expect
new packages will all behave this way from here out? It matters to me
because this new way assigns the IDs in a way that will vary depending
on what order I install packages, and that means I have to be more
careful with how I reconcile the passwd / shadow / group / gshadow
files between machines which would otherwise have identical lists, and
especially, I need to really watch out when reinstalling a machine and
then restoring /etc from backups.

It's not really a "problem" per se, but I'd very much like to know
what to expect here.