The build was failing following the addition of the sanity-check phase to the
Python buidl system.
* gnu/packages/python-build.scm (python-pypa-build)
[phases]{relax-requirements}: Add phase.
* gnu/packages/python-xyz.scm (python-pep517): Inherit from
python-pep517-bootstrap. Remove the inherited common fields.
(python-poetry-core, python-wheel)
(python-toml): Move to ...
* gnu/packages/python-build.scm: ... here, a new module.
(python-pep517-bootstrap): New package.
* gnu/local.mk (GNU_SYSTEM_MODULES): Register the new module.
* gnu/packages/python-xyz.scm (python-pep517): Inherit from
python-pep517-bootstrap. Remove the inherited common fields.
(python-poetry-core, python-wheel)
(python-toml): Move to ...
* gnu/packages/python-build.scm: ... here, a new module.
(python-pep517-bootstrap): New package.
* gnu/local.mk (GNU_SYSTEM_MODULES): Register the new module.