Process for upgrading the stdlib to a new cpython version

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... note: very similar to PyPy's process

1. check out the branch lib-python3

2. remove lib-python/3

3. copy the files from the pypy repo at the py3.x tip

4. git commit -m "import pypy hg:$(cd $PYPYDIR; hg sum | head -1 | cut -f2 -d' ')"

5. check out the branch to merge into

6. merge lib-python/3

7. follow process for integration