utils: Remove Nixpkgs helpers.

* guix/config.scm.in (%nixpkgs): Remove.
* guix/utils.scm (%nixpkgs-directory, nixpkgs-derivation,
  nixpkgs-derivation*): Remove.
* test-env.in: Export 'NIXPKGS'.
* tests/derivations.scm (%coreutils): Remove use of
  'nixpkgs-derivation'.
* tests/snix.scm (%nixpkgs-directory): New variable.
  Adjust users accordingly.

store: Add 'query-failed-paths' and 'clear-failed-paths' RPCs.

Suggested by Mark H Weaver <mhw@netris.org>.

* guix/store.scm (query-failed-paths, clear-failed-paths): New
  procedures.
* tests/guix-daemon.sh: Add test with daemon started with
  --cache-failures.

Merge branch 'core-updates'

Merge branch 'master' into core-updates

ui: Gracefully handle Unicode description strings.

Fixes <http://bugs.gnu.org/21536>.
Reported by Alex Kost <alezost@gmail.com>.

* guix/ui.scm (texi->plain-text): Wrap body in 'with-fluids'.
* tests/ui.scm ("package-description-string vs. Unicode"): New test.

tests: Unset 'LOCPATH' before running bootstrap program.

Reported by Mark H Weaver <mhw@netris.org>.

* tests/build-utils.scm ("wrap-program, one input, multiple calls"): Add
  'unsetenv' call.

tests: cran: Use cran-uri in expected output.

* tests/cran.scm: Expect output to use "cran-uri" procedure.

tests: Adjust snippet test to '.file_list' hack.

This is a followup to commit 140b4bc.

* tests/packages.scm ("package-source-derivation, snippet")[source]: Add
  'chmod' call for "..".

Merge branch 'master' into core-updates

lint: Report lonely parentheses.

* guix/scripts/lint.scm (%hanging-paren-rx): New variable.
  (report-lone-parentheses): New procedure.
  (%formatting-reporters): Use it.
* tests/lint.scm ("formatting: lonely parentheses"): New test.

Add (guix scripts).

* guix/ui.scm: Add missing copyright lines.
  (args-fold*, environment-build-options, %default-argument-handler,
  parse-command-line): Move to ...
* guix/scripts.scm: ...here.  New file.
* guix/scripts/archive.scm: Use it.
* guix/scripts/build.scm: Likewise.
* guix/scripts/download.scm: Likewise.
* guix/scripts/edit.scm: Likewise.
* guix/scripts/environment.scm: Likewise.
* guix/scripts/gc.scm: Likewise.
* guix/scripts/graph.scm: Likewise.
* guix/scripts/hash.scm: Likewise.
* guix/scripts/import/cpan.scm: Likewise.
* guix/scripts/import/cran.scm: Likewise.
* guix/scripts/import/elpa.scm: Likewise.
* guix/scripts/import/gem.scm: Likewise.
* guix/scripts/import/gnu.scm: Likewise.
* guix/scripts/import/hackage.scm: Likewise.
* guix/scripts/import/nix.scm: Likewise.
* guix/scripts/import/pypi.scm: Likewise.
* guix/scripts/lint.scm: Likewise.
* guix/scripts/package.scm: Likewise.
* guix/scripts/publish.scm: Likewise.
* guix/scripts/pull.scm: Likewise.
* guix/scripts/refresh.scm: Likewise.
* guix/scripts/size.scm: Likewise.
* guix/scripts/system.scm: Likewise.
* tests/ui.scm (with-environment-variable, "parse-command-line",
  "parse-command-line and --no options"): Move to ...
* tests/scripts.scm: ...here.  New file.
* Makefile.am (MODULES): Add guix/scripts.scm.
  (SCM_TESTS): Add tests/scripts.scm.
* po/guix/POTFILES.in: Add guix/scripts.scm.

lint: Add 'check-texinfo-markup' checker.

* guix/script/lint.scm (check-description-style): Check for invalid
  Texinfo markup.
* tests/lint.scm: Test it.

guix: lint: Check for meaningful origin file names.

* guix/scripts/lint.scm (check-source-file-name): New procedure.
  (%checkers): Add 'source-file-name' checker.
* tests/lint.scm ("source-file-name", "source-file-name: v prefix")
  ("source-file-name: valid", "source-file-name: bad checkout")
  ("source-file-name: good checkout"): New tests.
* doc/guix.texi (Invoking guix lint): Mention file name check.

guix: packages: Add origin-actual-file-name.

* guix/scripts/graph.scm (uri->file-name, node-full-name): Move origin file
  name logic to...
* guix/packages.scm (origin-actual-file-name): ...here.
* tests/packages.scm ("origin-actual-file-name")
  ("origin-actual-file-name, file-name"): New tests.

Merge branch 'master' into core-updates

guix: packages: Add transitive-input-references.

* guix/packages.scm (transitive-input-references): New procedure.
* gnu/packages/version-control.scm (package-transitive-propagated-labels*)
  (package-propagated-input-refs): Delete.
  (git)[arguments]: Adjust to transitive-input-references.

lint: Add 'license' checker.

* guix/scripts/lint.scm (check-license): New procedure.
  (%checkers): Add 'license' checker.
* tests/lint.scm ("license: invalid license"): New test.

tests: Fix typos.

* tests/derivations.scm ("substitutable-derivation?",
  "derivation-prerequisites-to-build and substitutes, local build"): Fix
  harmless typos.

monads: Fix 'liftN' fallback case.

Reported by Andy Wingo <wingo@igalia.com>.

* guix/monads.scm (define-lift) <fallback case>: Add missing #'.  Remove
  extra formal parameter.
* tests/monads.scm ("lift"): Add test with 'lift1' as a procedure.

graph: Add '--expression'.

* guix/scripts/graph.scm (%options, show-help): Add '--expression'.
  (guix-graph): Call 'read/eval-package-expression' for 'expression'
  pairs in OPTS.
* tests/guix-graph.sh: Add tests.
* doc/guix.texi (Invoking guix graph): Document it.