[Spack] format_fortran_code set wrong path for fprettify when using preinstalled Python from upstream

[jonasjucker]

def format_fortran_code(source: str) -> str:
    """Format fortran code using fprettify.

    The path to fprettify needs to be set explicitly for the
    non-Spack build process as Liskov does not activate a virtual environment.
    However, the PYTHON_PATH does not contain fprettify in a Spack build, hence the need for a special condition
    """
    bin_path = Path(PYTHON_PATH).parent
    if "spack" not in str(bin_path):
        fprettify_path = bin_path / "fprettify"
else:
        fprettify_path = "fprettify"
    args = [str(fprettify_path)]
    p1 = subprocess.Popen(args, stdout=subprocess.PIPE, stdin=subprocess.PIPE)
    return p1.communicate(source.encode("UTF-8"))[0].decode("UTF-8").rstrip()

is not correct, because PYTHONPATH points to /mch-environment/v3/linux-sles15-zen3/gcc-11.3.0/python-3.10.6-2df2crgellbveze7swvwq53xixcjle3i/bin/fprettify where fprettify does not exist.
Rather you find it in another location, since it is a separate Python module.

Why this work in case we install Python in the same build as icon4py is not known to me.

A possible solution could be to use some sort of which fprettify since it should be put in the build-env by Spack

[jonasjucker]

Fixed in #191