Dear developer,

systemd v258 brings an incompatible change that affects at least
pbuilder (with the non-default APT resolver):

systemd-run's --expand-environment= switch, which was disabled by
default when combined with --scope, has been changed to be enabled by
default. This brings cmdline expansion of transient scopes on par with
services.

It was announced in v257:

systemd-run's switch --expand-environment= which currently is disabled
by default when combined with --scope, will be changed in a future
release to be enabled by default.

It may deserve an entry in NEWS.Debian, since at least pbuilder's
developers didn't catch it.

Regards,