If you try to use the "predictable user-creation" part of fedora-usermgmt by: /usr/sbin/update-alternatives --set fedora-usermgmt \ /etc/fedora/usermgmt/scripts.shadow-utils it doesn't seem to change the behaviour at all because the wrapper script doesn't use the alternatives indirection. Attaching a patch which fixes it for me.
Created attachment 112053 [details] fedora-usermgmt-altenatives.diff
mmh... you should have a symlink | /etc/fedora/usermgmt/scripts -> /etc/alternatives/fedora-usermgmt which is created by the | /usr/sbin/update-alternatives --install /etc/fedora/usermgmt/scripts fedora-usermgmt /etc/fedora/usermgmt/scripts.legacy 60 %post scriptlet of the -shadow-utils subpackage. So the tools are right in looking for the script at '/etc/fedora/usermgmt/scripts'. Do you have a reproducible example which demonstrates your problems?
Okay, apologies - this must have somehow been my mistake. It works fine just as you describe.