bpo-33698: Fixed skipping of empty paths while reading pth [WIP].

[excitoon]

This patch fixes possibility to use imports from script directory.

--Follow up to Issue 29326.

Alexey erroneously broke adding empty paths to sys.path along with his fix of '\n' in sys.path.--

Official embeddable Python distributions do contain a blank line in its ._pth, and that previously allowed users to import modules from script directory.

https://bugs.python.org/issue29326

[the-knights-who-say-ni]

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[izbyshev]

This patch changes the documented ._pth behavior in backwards incompatible way. I'm not sure that we want to do that, but if we do, the documentation should be updated.

[zooba]

This change is incorrect and should not be merged.

[bedevere-bot]

A Python core developer has requested some changes be made to your pull request before we can consider merging it. If you could please address their requests along with any other requests in other reviews from core developers that would be appreciated.

Once you have made the requested changes, please leave a comment on this pull request containing the phrase I have made the requested changes; please review again. I will then notify any core developers who have left a review that you're ready for them to take another look at this pull request.

[zooba]

Please continue discussion on the bug (which will remain closed) so we can help figure out what you need and provide better alternatives.

[csabella]

@excitoon, thank you for your suggestion for improving CPython. Based on @zooba's comment and the discussion on the bug tracker, I'm going to close this issue.

[VadimPushtaev]

@csabella, do you really mean to highlight me?

[csabella]

@VadimPushtaev, thank you for asking. I apologize for my error. Not sure how I picked your name instead of the creator of the pull request.