bpo-40837: Fix email.utils.encode_rfc2231(string, None, None)

[spaceone]

encode_rfc2231() must not change the returned value if no transformation of the input was done.
This is also mentioned in the docstring of that function.

Actual behavior:

encode_rfc2231('foo bar', None, None)
'foo%20bar'

Expected behavior:

encode_rfc2231('foo bar', None, None)
'foo bar'

https://bugs.python.org/issue40837

[the-knights-who-say-ni]

Hello, and thanks for your contribution!

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@spaceone

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[orsenthil]

@spaceone , please sign the CLA and we will need a bugs.python.org issue number.
I worry about the clients that rely on the existing behavior.

[spaceone]

@spaceone , please sign the CLA and we will need a bugs.python.org issue number.
I worry about the clients that rely on the existing behavior.
I already signed the CLA and updated the bug number in the issue description. The bot doesn't update the status. I will add the bug number to the commit message as well.

[github-actions]

This PR is stale because it has been open for 30 days with no activity.

[spaceone]

@ezio-melotti why did you remove the CLA Signed label?

[spaceone]

This PR is stale because it has been open for 30 days with no activity.

jeah, lol. No merge since 6 years.

[bedevere-app]

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