test_brotli_version test broken when using pypi sdist

[apteryks]

Hi,

Running the test suite of 1.1.0.0 with pytest from its sdist (pypi hosted) source, I see:

_____________________________ test_brotli_version ______________________________

    def test_brotli_version():
        """
        Test that the __version__ starts with the
        Brotli version that's compiled with.
        """
        version_h = join(
            dirname(dirname(abspath(__file__))), "libbrotli/c/common/version.h"
        )
>       with open(version_h) as f:
E       FileNotFoundError: [Errno 2] No such file or directory: '/tmp/guix-build-python-brotlicffi-1.1.0.0.drv-0/brotlicffi-1.1.0.0/libbrotli/c/common/version.h'

test/test_compatibility.py:31: FileNotFoundError