The version of ‘python-setuptools’ in core-updates can't compress
files that pre-date 1980. This patch adds a procedure ‘(@ (guix
utils) change-file-timestamps-recursively)’ which can be added to
a packaging phase to set the atime and mtime to whatever you want.
I've taken that and applied it to both ‘criu’ and ‘sssd’, which
are the two packages I've noticed so far with this problem, but it
can be pretty safely assumed there are more. Unfortunately, I
couldn't see a way to find affected packages automatically,