>>> Configuring source in /var/tmp/portage/dev-python/soupsieve-2.3.2/work/soupsieve-2.3.2 ...
>>> Source configured.
>>> Compiling source in /var/tmp/portage/dev-python/soupsieve-2.3.2/work/soupsieve-2.3.2 ...
 * python3_7: running distutils-r1_run_phase distutils-r1_python_compile
python3.7 setup.py build -j 8
/usr/lib/python3.7/site-packages/setuptools/config/pyprojecttoml.py:102: _ExperimentalProjectMetadata: Support for project metadata in `pyproject.toml` is still experimental and may be removed (or change) in future releases.
  warnings.warn(msg, _ExperimentalProjectMetadata)
configuration error: `project.license` must be valid exactly by one definition (2 matches found):

    - keys:
        'file': {type: string}
      required: ['file']
    - keys:
        'text': {type: string}
      required: ['text']

DESCRIPTION:
    `Project license <https://www.python.org/dev/peps/pep-0621/#license>`_.

GIVEN VALUE:
    "MIT"

OFFENDING RULE: 'oneOf'

DEFINITION:
    {
        "oneOf": [
            {
                "properties": {
                    "file":

{                         "type": "string",                         "$$description": [                             "Relative path to the file (UTF-8) which contains the license for the",                             "project."                         ]                     }

                },
                "required": [
                    "file"
                ]
            },
            {
                "properties": {
                    "text":

{                         "type": "string",                         "$$description": [                             "The license of the project whose meaning is that of the",                             "`License field from the core metadata",                             "<https://packaging.python.org/specifications/core-metadata/#license>`_."                         ]                     }

                },
                "required": [
                    "text"
                ]
            }
        ]
    }
Traceback (most recent call last):
  File "setup.py", line 4, in <module>
    setuptools.setup()
  File "/usr/lib/python3.7/site-packages/setuptools/_init_.py", line 87, in setup
    return distutils.core.setup(**attrs)
  File "/usr/lib/python3.7/site-packages/setuptools/_distutils/core.py", line 122, in setup
    dist.parse_config_files()
  File "/usr/lib/python3.7/site-packages/setuptools/dist.py", line 854, in parse_config_files
    pyprojecttoml.apply_configuration(self, filename, ignore_option_errors)
  File "/usr/lib/python3.7/site-packages/setuptools/config/pyprojecttoml.py", line 54, in apply_configuration
    config = read_configuration(filepath, True, ignore_option_errors, dist)
  File "/usr/lib/python3.7/site-packages/setuptools/config/pyprojecttoml.py", line 120, in read_configuration
    validate(subset, filepath)
  File "/usr/lib/python3.7/site-packages/setuptools/config/pyprojecttoml.py", line 43, in validate
    raise error from None
ValueError: invalid pyproject.toml config: `project.license`
 * ERROR: dev-python/soupsieve-2.3.2::python-modules-kit failed (compile phase):