I think I see the source of the confusion. test_distutils fails because it runs in the build tree and without files installed. The test does not use the installed version of sysconfig, so it looks for ./Modules/ld_so_aix, which fails. The kludge from 2000 was trying to make the test work. But after installation, the kludge defines variables incorrectly to build Modules after Python is installed.

Because the distutils test is testing in tree and not the installed version of Python, it is not testing what the end user will experience. I am unsure about the best way to make the test pass.