guix hash: Interpret '-' as standard input.

* guix/scripts/hash.scm (guix-hash)[file-hash]: Special-case "-".
* tests/guix-hash.sh: Add test.
* doc/guix.texi (Invoking guix hash): Document it.

tests: Adjust pypi test to recent importer change.

This is a followup to b5c347ad3d83ee580c111bd14c80b469b0dcb294.

* tests/pypi.scm ("pypi->guix-package"): Expect 'propagated-inputs', not
'inputs'.
("pypi->guix-package, wheels"): Likewise.

tests: Skip 'pivot-root' test on Linux > 4.7.5.

* tests/syscalls.scm ("pivot-root"): Skip when 'uname' returns a
'utsname:release' > 4.7.5.

tests: Make sure child process of 'pivot-root' test exits.

* tests/syscalls.scm ("pivot-root"): Use 'test-equal'.  Wrap child body
in 'dynamic-wind'.

tests: Fix typo in 'with-graft' transformation test.

This is a followup to 645b9df858683dc05ffa04c9eb2fdc45ccef4a65.

* tests/scripts-build.scm ("options->transformation, with-graft"): Use
'with-graft', not 'with-input'.

lint: Suggest @code instead of quotes.

* guix/scripts/lint.scm (%quoted-identifier-rx): New variable.
(check-description-style)[check-quotes]: New procedure.
Use it.
* tests/lint.scm ("description: suggest ornament instead of quotes"):
New test.

container: Allow 'container-excursion' to the same namespaces.

Before that, 'container-excursion' would call 'setns' even when the
target namespace is the one the caller is already in, which would fail.

* gnu/build/linux-container.scm (container-excursion): Introduce
'source' and 'target'.  Compare the result of 'readlink' on these
instead of comparing file descriptors to decide whether to call
'setns'.
* tests/containers.scm ("container-excursion, same namespace"): New test.

grafts: Apply the right grafts in the presence of multiple outputs.

Fixes <http://bugs.gnu.org/24712>.

* guix/grafts.scm (cumulative-grafts): Add grafts for all the outputs of
DRV.
* tests/grafts.scm ("graft-derivation, replaced derivation has multiple
outputs"): New test.

guix build: Add '--with-graft'.

* guix/scripts/build.scm (transform-package-inputs/graft): New procedure.
(%transformations): Add 'with-graft'.
(%transformation-options): Likewise.
(show-transformation-options-help): Document it.
* tests/scripts-build.scm ("options->transformation, with-graft"): New
test.
* doc/guix.texi (Package Transformation Options): Document it.

graph: Add '%referrer-node-type'.

* guix/scripts/graph.scm (ensure-store-items): New procedure.
(%reference-node-type)[convert]: Use it.
(non-derivation-referrers): New procedure.
(%referrer-node-type): New variable.
(%node-types): Add it.
* tests/graph.scm ("referrer DAG"): New test.
* doc/guix.texi (Invoking guix graph): Document it.

grafts: 'graft-derivation' does now introduce grafts that shadow other grafts.

Partly fixes <http://bugs.gnu.org/24418>.

* guix/grafts.scm (cumulative-grafts)[graft-origin?]: New procedure.
[dependency-grafts]: Use it in new 'if' around recursive call.
* tests/grafts.scm ("graft-derivation, grafts are not shadowed"): New test.

packages: 'package-grafts' applies grafts on replacement.

Partly fixes <http://bugs.gnu.org/24418>.

* guix/packages.scm (input-graft): Compute 'new' with #:graft? #t.
(input-cross-graft): Likewise.
* tests/packages.scm ("package-grafts, indirect grafts, cross"): Comment
out.
("replacement also grafted"): New test.

utils: Support defaults in substitute-keyword-arguments.

* guix/utils.scm (collect-default-args, expand-default-args): New
syntax.
(substitute-keyword-arguments): Allow default value declarations.
* tests/utils.scm (substitute-keyword-arguments): New test.

utils: Fix default-keyword-arguments.

* guix/utils.scm (default-keyword-arguments): Properly test for present
keywords.
* tests/utils.scm (default-keyword-arguments): New test.

lint: 'cve' checker reports the replacement's vulnerabilities.

Before, 'guix lint -c cve' would report the vulnerabilities of the
original package while pretending they are the vulnerabilities of the
replacement.

* guix/scripts/lint.scm (check-vulnerabilities): Consider the package
replacement before calling 'package-vulnerabilities'.
* tests/lint.scm ("cve: vulnerability fixed in replacement version"):
New test.

grafts: Allow the replacement to have a different name.

* guix/build/graft.scm (replace-store-references): REPLACEMENT is now
the full string, not just the hash.
(rewrite-directory)[hash-mapping](valid-suffix?): Remove.
(hash+suffix): Rename to...
(hash+rest): ... this.  Change to return the whole string as the second
element of the list.  Adjust 'match-lambda' expression accordingly;
check whether the string length of the origin and replacement match.
* tests/grafts.scm ("graft-derivation, grafted item uses a different
name"): New test.
* doc/guix.texi (Security Updates): Update sentence on the name/version
restriction.

tests: Adjust 'guix build -S' test for source-less packages.

This is a followup to 8a54c0ec694ad6e22b155d167552b8fd0914e82d.

* tests/guix-build.sh: Allow 'guix build -S' to succeed with source-less
packages.  Check that the result is the empty string.

import: utils: Refactor license->symbol.

* guix/import/utils.scm (license->symbol): Work for all licenses.
* tests/import-utils.scm (license->symbol): Add test.

gexp: Add 'file-append'.

* guix/gexp.scm (<file-append>): New record type.
(file-append): New procedure.
(file-append-compiler): New gexp compiler.
* tests/gexp.scm ("file-append", "file-append, output")
("file-append, nested", "gexp->file + file-append"): New tests.
* doc/guix.texi (G-Expressions): Use it in 'nscd' and 'list-files'
examples.  Document 'file-append'.

guix hash: Add --exclude-vcs option.

* guix/scripts/hash.scm (show-help): Add help text for --exclude-vcs option.
(%options): Add --exclude-vcs option.
(guix-hash): Handle exclude-vcs option.
* doc/guix.texi ("Invoking guix hash"): Update doc.
* tests/guix-hash.sh: Add test.

Co-authored-by: Ludovic Courtès <ludo@gnu.org>