[issue21907] Update Windows build batch scripts

[Roundup Robot]

Roundup Robot added the comment:

New changeset 06589e81fd56 by Zachary Ware in branch 'default':
Issue #21907: Make the buildbot clean script always return 0.
http://hg.python.org/cpython/rev/06589e81fd56

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue21907>
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