[issue2090] __import__ with fromlist=[''] causes double initialization of modules

[George Sakkis]

George Sakkis <george.sakkis at gmail.com> added the comment:

Just bitten by this (through a 3rd party library that uses this pattern) and I'm wondering why it was closed as invalid. Passing a non-empty fromlist string also imports the tail module but without the side effect of double import, so it's not generally harmful. More surprisingly, a colleague discovered accidentally that the same behavior happens if you pass one or more slashes: __import__('pkg', fromlist=['', '/', '//']) imports 'pkg', 'pkg.', 'pkg./' and 'pkg.//' !

I'm not arguing that using fromlist to import the tail module is not a hack, but the behavior for empty strings and slashes (and whatever else causes multiple imports) is clearly a bug. Unless someone is actually relying on this double import behavior (very unlikely), I think it should be fixed.

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nosy: +gsakkis
versions: +Python 2.7

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<http://bugs.python.org/issue2090>
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