[Compiler-sig] ast branch

[Jeremy Hylton]

Thanks for the clue about the Raise statement in ast.c.  It was
completely broken, and fixing it provided a lot of progress.  Running 
"python -v" got to an interpreter prompt:

'import site' failed; traceback:
Traceback (most recent call last):
  File "/home/jeremy/src/python-ast/build-pydebug/../Lib/site.py",
line 0, in <module>
    File "/home/jeremy/src/python-ast/build-pydebug/../Lib/site.py",
line 0, in <module>
  File "/home/jeremy/src/python-ast/build-pydebug/../Lib/os.py", line
0, in <module>
    File "/home/jeremy/src/python-ast/build-pydebug/../Lib/os.py",
line 0, in <module>
NameError: name '_Environ' is not defined
Python 2.3a0 (#71, Apr  1 2003, 23:20:02)
[GCC 2.96 20000731 (Red Hat Linux 7.3 2.96-113)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
filename=<stdin>
>>>

It's not perfect, but it's nice to actually survive startup.  As we've
noted, it would sure be handy to have some line numbers.

Jeremy