The rationale is to reduce the number of derivations built per pack to ideally
one, to minimize storage requirements. The number of derivations had gone up
with 68380db4 ("pack: Extract populate-profile-root from
self-contained-tarball/builder.") as a side effect to improving code reuse.
* guix/scripts/pack.scm (guix): Add commentary comment.
(populate-profile-root, self-contained-tarball/builder): Extract to...
* guix/build/pack.scm (populate-profile-root): ... this, and...
(build-self-contained-tarball): ... that, adjusting for use on the build side.
(assert-utf8-locale): New procedure.
(self-contained-tarball, debian-archive, rpm-archive): Adjust accordingly.
Reviewed-by: Ludovic Courtès <ludo@gnu.org>