[issue20812] Explicitly cover application migration in the 2->3 guide

[Brett Cannon]

Brett Cannon added the comment:

Something like this should go at the top almost as a tl;dr to get the point across that regardless of the state of your dependencies, start writing Python 3-compatible code **today** and if you must update old code piecemeal. I'll add something next time I have time (should be Friday).

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assignee:  -> brett.cannon

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue20812>
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