It is suggested in https://bugs.python.org/issue23251
that only a core Python developer may reflow paragraphs
while submitting patches for the Python documentation.

It should be codified in devguide: I haven't found the
word *reflow* in it.

That wording is a bit strong :).

On that issue I requested a patch without the reflow, because I prefer that.  Personally, I think it is in fact worth noting in the devguide that it is better for doc patches to not reflow paragraphs so that it is easier to see just the changed text in the patch file and in the 'hg diff' output.

However, since reitveld can handle reflowed paragraphs, other developers my not agree with me on this.

For normal paragraphs, long and short lines make no difference to Sphinx and subsequent output.  I would like to know and have documented when (how uneven the lines) a reflow is otherwise considered necessary.

For patches to be reviewed (whether submitted by a core developer or not), there should be as little spurious changes as possible.  In the final commit, it's ok, but not mandatory, to reflow the paragraphs.

Agreed with what Georg said and I think the devguide can be update accordingly.

https://bugs.python.org/issue18041 also provides related insights. Ideally, a patch for this issue should address and close both issues.

Moved to https://github.com/python/devguide/issues/12