The error message is "'utf8' codec can't decode byte 0xeb", and the message contained a ë. Byte 0xeb in the *ISO-8859-1* character encoding is ë!
This means that it is very likely that the message is not encoded with UTF-8 at all, but with ISO-8859-1, and Gwibber for some reason tries to decode the message using the wrong character encoding!
In my own error message posted above the byte it can't decode using UTF-8 is 0xe1, which is á in ISO 8859-1. I think it's likely we have found the bug.
Aha, a clue!
The error message is "'utf8' codec can't decode byte 0xeb", and the message contained a ë. Byte 0xeb in the *ISO-8859-1* character encoding is ë!
This means that it is very likely that the message is not encoded with UTF-8 at all, but with ISO-8859-1, and Gwibber for some reason tries to decode the message using the wrong character encoding!
In my own error message posted above the byte it can't decode using UTF-8 is 0xe1, which is á in ISO 8859-1. I think it's likely we have found the bug.