def METHOD_NAME(self, tmpdir):
    """
    Installing two packages sharing the same namespace, one installed
    naturally using pip or `--single-version-externally-managed`
    and the other installed using `develop` should leave the namespace
    in tact and both packages reachable by import.
    """
    pkg_A = namespaces.build_namespace_package(tmpdir, 'myns.pkgA')
    pkg_B = namespaces.build_namespace_package(tmpdir, 'myns.pkgB')
    target = tmpdir / 'packages'
    # use pip to install to the target directory
    install_cmd = [
        sys.executable,
        '-m',
        'pip',
        'install',
        str(pkg_A),
        '-t',
        str(target),
    ]
    subprocess.check_call(install_cmd)
    self.install_develop(pkg_B, target)
    namespaces.make_site_dir(target)
    try_import = [
        sys.executable,
        '-c',
        'import myns.pkgA; import myns.pkgB',
    ]
    with test.test.paths_on_pythonpath([str(target)]):
        subprocess.check_call(try_import)
    # additionally ensure that pkg_resources import works
    pkg_resources_imp = [
        sys.executable,
        '-c',
        'import pkg_resources',
    ]
    with test.test.paths_on_pythonpath([str(target)]):
        subprocess.check_call(pkg_resources_imp)