* guix/derivations.scm (derivation-hash): Add comment as to why we keep
the plain `sha256' call.
* guix/scripts/download.scm (guix-download): Use `port-sha256' instead
of (compose sha256 get-bytevector-all).
* guix/scripts/refresh.scm (update-package): Likewise.
* guix/gnu-maintenance.scm (download-tarball): Add a 'key-download'
keyword argument and pass it to 'gnupg-verify*'. Make
'archive-type' a keyword argument.
(package-update): Add a 'key-download' keyword argument. Pass
'archive-type' and 'key-download' keyword arguments to
'download-tarball'.
* guix/gnupg.scm: Import (ice-9 i18n) and (guix ui).
(gnupg-verify*): Add a 'key-download' keyword argument and adjust
'gnupg-verify*' to use it. Make 'server' a keyword argument.
* guix/scripts/refresh.scm (show-help, %options): Add and document
'--key-download'.
(update-package): Add a 'key-download' keyword argument and pass it
to 'package-update'.
(guix-refresh): Pass 'key-download' to 'update-package'. Limit
lines to a maximum of 79 characters.
* guix/scripts/refresh.scm (%options): Add `--key-server' and `--gpg'.
(show-help): Update accordingly.
(update-package): New procedure, formerly in `guix-refresh'.
(guix-refresh): Use it. Parameterize `%openpgp-key-server' and
`%gpg-command'.
* guix/scripts/refresh.scm (guix-refresh): When updating a source file,
gracefully handle the case where TARBALL is #f.
Reported by Nikita Karetnikov <nikita@karetnikov.org>.
* guix/scripts/refresh.scm (%options): Add `--select'.
(show-help): Likewise. Augment initial help text.
(guix-refresh)[core-package?]: New procedure.
Use it when selecting packages.
