gnu: intel-xed: Adjust build phase.

* gnu/packages/assembly.scm (intel-xed)
[phases]: Delete trailing #t.
{build}: Do not read PYTHONPATH from environment.

gnu: solaar: Do not read PYTHONPATH from environment.

* gnu/packages/admin.scm (solaar)
[phases]{setenv-PATH}: Do not read PYTHONPATH from environment.

gnu: python2-virtualenv: Fix build.

* gnu/packages/python-xyz.scm (python2-virtualenv)[arguments]{phases}: Remove
argument.

gnu: python2-packaging-bootstrap: Add missing dependency

* gnu/packages/python-xyz.scm (python2-packaging-bootstrap)
[propagated-inputs]: Add python2-six-bootstrap.

gnu: python-traceback2: Add missing dependency.

* gnu/packages/python-xyz.scm (python-traceback2)[propagated-inputs]:
Add python-six.

gnu: python-packaging-bootstrap: Remove dependency.

* gnu/packages/python-xyz.scm (python-packaging-bootstrap) [arguments]:
Remove dependency from setup.py, which we do not provide for this
variant.

gnu: python-automat: Remove broken console script.

* gnu/packages/python-xyz.scm (python-automat) [arguments]: Patch
setup.py.

gnu: python-twisted: Remove broken console scripts.

* gnu/packages/python-xyz.scm (python-twisted) [arguments]: Patch
setup.py.

gnu: python-idna-ssl: Add missing input.

* gnu/packages/python-xyz.scm (python-idna-ssl)[propagated-inputs]: Add
python-idna.

gnu: python-traitlets: Add missing input.

* gnu/packages/python-xyz.scm (python-traitlets)[propagated-inputs]:
Add python-six.

gnu: python-black: Remove blackd.

* gnu/packages/python-xyz.scm (python-black) [arguments]: Add new phase
to prevent installation of blackd.

gnu: python-websockets: Fix Python package name.

* gnu/packages/python-web.scm (python-websockets) [arguments]: Add new
phase to fix package name.

gnu: python-slugify: Add missing input.

* gnu/packages/python-web.scm (python-slugify) [propagated-inputs]: Add
python-text-unidecode.

gnu: python-pyfakefs: Disable unreliable test

* gnu/packages/check.scm (python-pyfakefs) [arguments]: Add new phase to
skip single test.

gnu: python-pytest-pep8: Fix package.

* gnu/packages/check.scm (python-pytest-pep8)[arguments]: Remove
dependency on pytest-cache and add proper 'check phase.

gnu: python-fixtures-bootstrap: Do not sanity check.

* gnu/packages/check.scm (python-fixtures-bootstrap)
[phases]{sanity-check}: Delete.

gnu: python-pytest-xdist: Add missing input, relax pytest requirement.

* gnu/packages/check.scm: (python-pytest-xdist)
[arguments]: Relax pytest version requirements.
[propagated-inputs]: Add python-pytest-forked.

build/python: Add a sanity check phase.

Add a new phase validating the usability of installed Python packages.

* gnu/packages/aux-files/python/sanity-check.py: New file.
* Makefile.am (AUX_FILES): Register it.
* guix/build-system/python.scm (sanity-check.py): New variable.
(lower): Add the script as an implicit input.
* guix/build/python-build-system.scm: Remove trailing #t.
(sanity-check): New phase.
(%standard-phases): Use it.
* tests/builders.scm: (make-python-dummy)
(dummy-ok, dummy-dummy-nosetuptools, dummy-fail-requirements)
(dummy-fail-import, dummy-fail-console-script): New variables.
("python-build-system: dummy-ok")
("python-build-system: dummy-dummy-nosetuptools")
("python-build-system: dummy-fail-requirements")
("python-build-system: dummy-fail-import")
("python-build-system: dummy-fail-console-script"): Add tests.

build/python: Adjust wrap phase to use the new GUIX_PYTHONPATH.

* guix/build/python-build-system.scm (wrap): Adjust to use the new
GUIX_PYTHONPATH.  Remove trailing #t.

build/python: Add the installation bin directory to PATH.

This also to reduce the need for boilerplate code found in check phase
overrides.

* guix/build/python-build-system.scm (add-install-to-path): New phase.
(%standard-phases): Order it before the check phase.