Message12115

I have this in a good state now and think I've shaken out a lot of latent bugs and divergences from CPython. Hopefully, next time we have to work on this logic, we'll understand it easily, and have a comparator in CPython. (It's confused me from the start, and I know I made it subtly worse.)

I'll commit as it now is, but I have the following to-do list:

1. Actually remove SystemRestart (as discussed on jython-dev). What I did was restore it, half-working, but only so I can kill it in one easily-identifiable change.

2. Factor out (into PyOS.java?) utility and OS-like things it is safe to do before Python types exist. I am influenced here by https://www.python.org/dev/peps/pep-0432/ . At the moment, too many things are in Py.java and PySystemState, which, as soon as you touch them, bring the whole Python type system prematurely to life.

3. Implement os.environ and the registry in pre-Python space so we can use them for configuration before starting Python.

4. Reconcile the several ways of deciding if the console is interactive into one (pre-Python) strategy.

5. Check I've not broken Jython on Linux.

6. Check all this in an environment with non-ascii installation and user paths.