[issue12908] Update dev-in-a-box for new coverage steps

[Ezio Melotti]

Changes by Ezio Melotti <ezio.melotti at gmail.com>:


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nosy: +eli.bendersky, eric.araujo, ezio.melotti, terry.reedy

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue12908>
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