'Return an sdist with a setup_requires dependency (of something that
doesn\'t exist)'

@staticmethod
@contextlib.contextmanager
def create_sdist():

    with tempdir_context() as dir:
        dist_path = os.path.join(dir, 'setuptools-test-fetcher-1.0.tar.gz')
        make_trivial_sdist(dist_path, textwrap.dedent('\n                                                                                import    setuptools\n                                                                                setuptools.setup(\n                                                                                                name="setuptools-test-fetcher",\n                                                                                                version="1.0",\n                                                                                                setup_requires    =    [\'does-not-exist\'],\n                                                                                )\n                                                                ').lstrip())
        (yield dist_path)
