[NegativeK]

Python has a CLA that allows the PSF board to relicense the code to "any other open source license approved by unanimous vote".

[lupusreal]

Legally speaking, once they own the copyright, is there anything stopping the PSF from selling out and changing their policy to permit proprietary licensing?

I have this same concern with GNU. I can imagine a future where some key figures have died or retired and the new org sells out and changes the license to something RMS never would have agreed to.

[cowsandmilk]

The PSF Contributor Agreement doesn’t assign copyright to the PSF, so your question doesn’t apply.

Text from their contributor agreement:

> PSF understands and agrees that Contributor retains copyright in its Contributions.

[NegativeK]

To go along with the other response, they don't own your copyright -- but I don't know if the language in the Python CLA actually holds them to the "we can only relicense to open source licenses" if challenged in a court.

But that's not really a risk I care about. The PSF is a nonprofit that's clearly aimed at being a nonprofit, and a Future Evil Board is beyond what I'm going to worry about.