Would this be too general catch the expected error message? In test, a possible response error message contains content "Invalid or expired token", if Pagure.io actually responses this content when a token is invalid or expired, it would be good just to match this content as much as possible, in case '\btoken\b' matches any other potential unrelated messages that just contains a word "token".

Thanks for the comment. Actually, it was my original purpose - to catch all error messages related to tokens.
Of course, there could be other different messages, that refer to different errors than invalid or expired token (missing token is covered elsewhere), but the Pagure message is still shown, and as a hint, there is added one sentence with context "For invalid or expired token refer to ...".
OK, I did the search pattern more specific as per your comment, but there is danger in case that Pagure will change the error wording, the hint will silently disappear. And that is, in my opinion, better than showing this hint when it is not 100% relevant.

I agree with not showing the message unless we are sure it is relevant. Misleading errors confuse people a lot.

Looks good to me.