Warn of mistaken trailing commas creating tuples

[pylint-bot]

Originally reported by: Anonymous

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As seen on the previous issue tracker here: http://www.logilab.org/92253.

The issue has bitten me a few times now. As mentioned in the old issue/ticket, something like:

#!python

>>> x = 1,    # Syntactically valid, but probably not what most programmers mean
>>> x
(1,)

I believe this is a worthy thing to warn about because there is already more explicit syntax in Python for tuple initialization with parentheses.

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• Bitbucket: https://bitbucket.org/logilab/pylint/issue/300