Jean-Paul Calderone

I suggest something like a `returnConnectionPredicate` which is consulted inside `_putConnection` after the other checks have passed. It is called with the protocol and if it returns true, the connection...

> I see two possible answers to that question, either we add a another callback which is called from '_removeConnection', or we store the metadata in the connection object. A...

> Instead of having the function return the new value, I would like to give each connection a dict for metadata which is passed to the checker, as the dict...

c902ced was reverted by c16e7af497442a178b91dc5179a59eb0d798c1a8

It looks like the DNS part of this is fine but then `twisted.mail.relaymanager.MXCalculator` can't handle more than one MX record on Python 3. On Python 2 `Record_MX` was probably ordered...

I see there is a cleanup-waker-3063-3 but it is quite conflicted with current trunk. Perhaps still useful as reference, though.

Additionally, the cause of this error is not very discoverable. The error message doesn't tell you what the difference is, just that there is one. The documentation doesn't seem to...

It appears you are running the test suite with pytest. Instead, run it like this: `python -m twisted.trial klein` or `tox -e py38`. Feel free to re-open if the issue...

On NixOS with Python 3.8.13 and 3.10.5 I tried to reproduce with: ``` pip install zope-interface==5.4.0 attrs==22.1.0 hyperlink==21.0.0 incremental==21.3.0 werkzeug==2.2.2 hypothesis==6.54.4 twisted==22.4.0 tubes==0.2.1 treq==22.2.0 klein==21.8.0 pip install -e klein-checkout python...

However, with Klein 21.8.0 I did reproduce the failure.