+# We want to make sure to have rpm with new dbpath used
+Requires(post): rpm >= 4.13

You still can't be sure to have an rpm with a new path with this requires.

There is simply no symbol there guaranteeing that you have an RPM with the new dbpath.

+  mv -f %{_dbpath}/alternatives/* /var/lib/alternatives/ || :
+  rmdir %{_dbpath}/alternatives ||:

I wonder if it were not safer to use the old admindir here, instead of relying on the 'changing' dbpath.

ALL systems have the old u-a files accessible under /var/lib/rpm/alternatives (with new dbpath via symlink, wihtout new dbpath it is there directly)

You would probably save yourself a lot of headaches (and the weird dependency on a specifc rpm version which is still no guarantee)

see sr#544378