doc: Mention 'guix refresh -u' for third-party channels.

* doc/guix.texi (Invoking guix refresh): Show how to run 'guix refresh
-u' on a third-party channel.

import: json: Add #:timeout to 'json-fetch'.

* guix/import/json.scm (json-fetch): Add #:timeout and pass it to
'http-fetch'.

import: utils: 'call-with-networking-exception-handler' doesn't unwind.

That way backtraces show where the error actually originates from.

* guix/import/utils.scm (call-with-networking-exception-handler):
Rewrite using 'with-exception-handler'.

tests: pypi: Rewrite tests using a local HTTP server.

* guix/import/pypi.scm (%pypi-base-url): New variable.
(pypi-fetch): Use it.
* tests/pypi.scm (foo-json): Compute URLs relative to '%local-url'.
(test-json-1, test-json-2, test-source-hash): Remove.
(file-dump): New procedure.
(with-pypi): New macro.
("pypi->guix-package, no wheel")
("pypi->guix-package, wheels")
("pypi->guix-package, no usable requirement file.")
("pypi->guix-package, package name contains \"-\" followed by digits"):
Rewrite using 'with-pypi'.

tests: http: Allow responses to specify a path.

* guix/tests/http.scm (%local-url): Add #:path parameter and honor it.
(call-with-http-server)[responses]: Add extra clause with 'path'.
[bad-request]: New variable.
[server-body]: Handle three-element clauses.
Wrap 'run-server' call in 'parameterize'.

tests: pypi: Factorize tarball and wheel file creation.

* tests/pypi.scm (sample-directory): New variable.
(pypi-tarball, wheel-file): New procedures.
("pypi->guix-package, no wheel")
("pypi->guix-package, wheels")
("pypi->guix-package, no usable requirement file.")
("pypi->guix-package, package name contains \"-\" followed by digits"):
Use them.

transformations: Add "--tune" to "--help-transform".

* guix/transformations.scm (show-transformation-options-help/detailed):
Add '--tune'.

nls: Update translation keys for guix gc.

* po/*/*.po (guix/scripts/gc.scm): Round MiBs in user feedback.

Signed-off-by: Florian Pelz <pelzflorian@pelzflorian.de>

guix gc: Round MiBs in user feedback.

* guix/scripts/gc.scm (guix-gc): Round MiBs in user feedback.

Signed-off-by: Florian Pelz <pelzflorian@pelzflorian.de>

gnu: r-desctools: Update to 0.99.49.

* gnu/packages/statistics.scm (r-desctools): Update to 0.99.49.
[propagated-inputs]: Add r-withr.

gnu: r-rrcov: Update to 1.7-3.

* gnu/packages/statistics.scm (r-rrcov): Update to 1.7-3.

gnu: r-rcpparmadillo: Update to 0.12.4.0.0.

* gnu/packages/statistics.scm (r-rcpparmadillo): Update to 0.12.4.0.0.

gnu: r-knitr: Update to 1.43.

* gnu/packages/statistics.scm (r-knitr): Update to 1.43.

gnu: r-markdown: Update to 1.7.

* gnu/packages/statistics.scm (r-markdown): Update to 1.7.

gnu: r-matrix: Update to 1.5-4.1.

* gnu/packages/statistics.scm (r-matrix): Update to 1.5-4.1.

gnu: r-cartogram: Update to 0.3.0.

* gnu/packages/cran.scm (r-cartogram): Update to 0.3.0.

gnu: r-zoib: Update to 1.6.

* gnu/packages/cran.scm (r-zoib): Update to 1.6.

gnu: r-crul: Update to 1.4.0.

* gnu/packages/cran.scm (r-crul): Update to 1.4.0.

gnu: r-dismo: Update to 1.3-14.

* gnu/packages/cran.scm (r-dismo): Update to 1.3-14.

gnu: r-rgeos: Update to 0.6-3.

* gnu/packages/cran.scm (r-rgeos): Update to 0.6-3.