* guix/scripts/package.scm (%default-options): Add `substitutes?'. (show-help, %options): Add and document `--no-substitutes'. (guix-package): Call `set-build-options' to honor `substitutes?'.
* guix/scripts/package.scm (%default-options): Add `substitutes?'. (show-help, %options): Add and document `--no-substitutes'. (guix-package): Call `set-build-options' to honor `substitutes?'.