[issue17329] Document unittest.SkipTest

[Brett Cannon]

New submission from Brett Cannon:

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assignee: docs at python
components: Documentation
messages: 183262
nosy: brett.cannon, docs at python, ezio.melotti, michael.foord, zach.ware
priority: normal
severity: normal
stage: needs patch
status: open
title: Document unittest.SkipTest
versions: Python 3.4

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue17329>
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