This reverts commit 4c0cc7bed3.
Fixes <https://bugs.gnu.org/41116>.
Reported by Alex Sassmannshausen <alex@komputilo.eu>.
The problem is that reconfiguring on a system running Shepherd < 0.8.0
would lead to an error, due to #:file-creation-mask not being supported.
The error is rather harmless: it prevents service upgrade but the system
itself is upgraded.
We can reinstate that commit eventually, once #:file-creation-mask has
become widespread.
5aa4d2dcf2