Background: we'd like to enable running 'make touch' on the bots before 'make -jN', to avoid problems with scripts that auto-generate code for the Python build (bootstrapping). pydev thread: https://mail.python.org/pipermail/python-dev/2013-September/128992.html

A couple of issues are prerequisites:

1. Fix the asdl dependencies in .hgtouch:

Include/ast.h: Parser/Python.asdl Parser/asdl.py Parser/asdl_c.py
Python/Python-ast.c: Include/ast.h

The file Include/ast.h is not, in fact, auto-generated. But Include/Python-ast.h *is*, and it does not appear in this file.

2. Make sure 'hg touch' itself runs on Python 2.4 because that's what some bots have (and other older systems like RHEL 5)