import: cran: Add copyright notice.

Add notice for commit d882c23.

import: cran: Avoid HTTP redirect.

* guix/import/cran.scm (cran-fetch): Add trailing slash in URL to avoid
  HTTP redirect.

import: cran: Add updater.

* guix/import/cran.scm (downloads->url, nodes->text): New procedures.
  (cran-sxml->sexp): Use them.  Remove equivalent local code.
  (latest-release, cran-package?): New procedures.
  (%cran-updater): New variable.
* guix/scripts/refresh.scm (%updaters): Add %CRAN-UPDATER.
* doc/guix.texi (Invoking guix refresh): Mention CRAN.

refresh: Remove exception catch-all.

* guix/scripts/refresh.scm (update-package): Remove 'catch #t'.

refresh: Add '--type' option.

* guix/scripts/refresh.scm (%options, show-help): Add --type.
  (lookup-updater): New procedure.
  (update-package): Add 'updaters' parameter and honor it.
  (guix-refresh)[options->updaters]: New procedure.
  Use it, and honor --type.

import: elpa: Add updater.

* guix/import/elpa.scm (latest-release, package-from-gnu.org?): New
  procedures.
  (%elpa-updater): New variable.
* guix/scripts/refresh.scm (%updaters): Add %ELPA-UPDATER.

import: elpa: Use 'http-fetch/cached' to retrieve the archive.

* guix/import/elpa.scm (elpa-fetch-archive): Set %HTTP-CACHE-TTL to 6
  hours.
  (call-with-downloaded-file): Use 'http-fetch/cached' instead of
  'url-fetch'.

gnu-maintenance: Generalize, leading to (guix upstream).

* guix/gnu-maintenance.scm (<gnu-release>): Remove.
  (coalesce-releases): Move to upstream.scm.  Rename to
  'coalesce-sources'; adjust callers.
  (releases, latest-release): Return <upstream-source> objects instead
  of <gnu-release> objects.
  (latest-release*, non-emacs-gnu-package?): New procedures.
  (gnu-release-archive-types): Remove.
  (%gnu-updater): New variable.
  (package-update-path, download-tarball, package-update,
  update-package-source): Move to...
* guix/upstream.scm: ... here.  New file.
* Makefile.am (MODULES): Add it.
* po/guix/POTFILES.in: Replace gnu-maintenance.scm with upstream.scm.
* guix/scripts/refresh.scm (%updaters): New variable.
  (update-package): Adjust to new 'package-update' interface.
  (guix-refresh): Adjust to new 'package-update-path'.  Remove
  'false-if-exception' around it.

http-client: '%http-cache-ttl' is really a parameter.

Fixes a typo in commit 739ab68 that made it a procedure returning a
parameter.

* guix/http-client.scm (%http-cache-ttl): Turn into a parameter.

Add 'guix challenge'.

* guix/scripts/challenge.scm, tests/challenge.scm: New files.
* Makefile.am (MODULES): Add the former.
  (SCM_TESTS): Add the latter.
* doc.am (SUBCOMMANDS): Add 'challenge'.
* doc/guix.texi (Substitutes): Add xref to 'guix challenge'.
  (Invoking guix challenge): New node.
* doc/contributing.texi (Submitting Patches): Add note about using 'guix
  challenge'.
* po/guix/POTFILES.in: Add guix/scripts/challenge.scm.

substitute: Expose narinfo access.

* guix/scripts/substitute.scm: Export <narinfo> accessors.
  (narinfo-hash->sha256): New procedure.
  (cache-narinfo!): Ignore EACCES exceptions.

guix archive: Add '--extract'.

* guix/scripts/archive.scm (show-help, %options): Add --extract.
  (guix-archive): Honor it.
* tests/guix-archive.sh: Test it.
* doc/guix.texi (Invoking guix archive): Document it.

gnu-maintenance: Fix file descriptor leak.

* guix/gnu-maintenance.scm (official-gnu-packages): Close the port
  returned by FETCH.

gnu-maintenance: Use 'http-fetch/cached' by default.

This speeds up operations like 'guix lint -c gnu-description'.

* guix/gnu-maintenance.scm (official-gnu-packages): Add 'fetch'
  parameter and honor it.  Default to 'http-fetch/cached'.

http-client: Add 'http-fetch/cached'.

* guix/utils.scm (cache-directory): New procedure.
* guix/http-client.scm (%http-cache-ttl): New variable.
  (http-fetch/cached): New procedure.

syscalls: Fix ABI mismatch for 'clone'.

Fixes <http://bugs.gnu.org/21694>.

* guix/build/syscalls.scm (clone): Change 'syscall' parameter types to
  LONG, UNSIGNED-LONG, or '*; make sure it has 6 parameters.  Adjust
  caller accordingly.

guix system: Add 'dmd-graph' command.

* guix/scripts/system.scm (dmd-service-node-label,
  dmd-service-node-type, export-dmd-graph): New procedures.
  (show-help): Add 'dmd-graph'.
  (guix-system)[parse-sub-command]: Likewise.
  Honor it.
* doc/guix.texi (Invoking guix system): Document it.
  (dmd Services): Add an illustration and explanation.
* doc/images/dmd-graph.dot: New file.
* doc.am (DOT_FILES): Add it.

guix system: Add 'extension-graph' command.

* guix/scripts/system.scm (service-node-label, service-node-type,
  export-extension-graph): New procedures.
  (guix-system)[parse-sub-command]: Add 'extension-graph'.
  Honor it.
  (show-help): Add 'extension-graph'.
* doc/guix.texi (Invoking guix system): Document it.
  (Service Composition): Add cross-reference.

graph: 'export-graph' takes a #:reverse-edges? parameter.

* guix/scripts/graph.scm (export-graph): Add #:reverse-edges? parameter
  and honor it.

build-system/gnu: dist-package: Use 'autoconf-wrapper'.

* guix/build-system/gnu.scm (dist-package): Use AUTOCONF-WRAPPER instead
  of AUTOCONF.