Mailman strips out format=flowed from the text/plain messages

It looks like mailman releases prior to 2.1.10 strip out the format=flowed content-type argument – see the bug report [1]. This means that e-mails which are sent to the mailing list cannot be reflowed properly, resulting either in lines which are too short or too long, depending on what the sender's agent has used.

Is there any possibility of upgrading mailman?

[1] https://bugs.launchpad.net/mailman/+bug/266341