[issue17306] Improve the way abstract base classes are shown in help()

[Éric Araujo]

Changes by Éric Araujo <merwok at netwok.org>:


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nosy: +eric.araujo
versions: +Python 3.4 -Python 2.7

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue17306>
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