Fix for Python library path problem

[Fred Wright]

On Wed, 27 Sep 2017, Eric S. Raymond via devel wrote:

> I've pushed a fix for Fred Wright's FixConfig class that seems to
> solve the problem of incorrect Python library locations.
>
> I tested it with no --prefix option and with --prefix=/usr,
> using install --destdir=/tmp/ntp.
>
> Gary, please verify that this addresses your FHS concerns.
>
> Fred, please tell me if you think this is broken in some obscure way.

I'm not sure about "obscure", but if the result isn't in sys.path, then
it's back to the same old problem.

Looking at the waf change that introduced the trouble, it looks like it
was mainly motivated by wanting to allow --prefix to influence the results
(even though one can always supply --pythondir and --pythonarchdir), and
they simply caused the no --prefix case to pas the default prefix instead
of nothing, perhaps without realizing how this screws up the result.

AFAICT, Python simply doesn't follow FHS on Linux.  It may have the
attitude that the fact that the paths have "pythonX.Y" in them makes them
"owned" by Python, and hence exempt from the usual FHS rules.  Whether one
agrees with that philosophy or not, it's the way Python is set up (on
Linux, anyway), and going against it can be expected to cause trouble.

Take a look at the "non-FHS-compliant" Python library location on your
system, and see how many *other* packages are being installed there.
*Everyone* is going with Python rather than FHS on this issue, and if you
want it fixed, you should convince the Python folks (or whoever configures
the Linux Python installs) to fix it.

Fred Wright