Oh really? So the release needs to be major. It should be 1.3... maybe also 2.0. Because it is not backward compatible.
It would be preferable to also increase the version of the API... but it's a tiny change I'd say...

You mean it's not compatible because the status code change? Will it break anyone?

Yeah, I mean that. I'm not sure it will break something, but it might be. Maybe some bot or something is checking that status code? We cannot know for sure.
It's a bit overkill to change the version of the API for this change IMHO. But I would still release at least as 1.3.

Hmm, let me check, I remember that I've seen someone use 500 error code somewhere but it can be unrelated.

It's fix for #460 which was broken in previous release (unhandled retry failure).

So it's bugfix, no need to bump other than patch version number.

On the other hand, there is a new feature so I could at least bump the minor version.

I've also create issue to handle other retry failure and refactor the handling for RemoteRule (#479).

+1