[issue18730] suffix parameter in NamedTemporaryFile silently fails when not prepending with a period

[Serhiy Storchaka]

Changes by Serhiy Storchaka <storchaka at gmail.com>:


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nosy:  -serhiy.storchaka

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue18730>
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