I definitely contributed to this :nauseated_face: ...
Seems that the function that I am using (`add_contact_alias()` with 3 parameters) never added `[` and `]` around IPv6 addresses. I took it as quite OK, and the rule, since the alias encoding uses `~` as separator between IP and port, so there was no need to surround the IPv6 address. In `handle_ruri_alias()` then I patched it to add them for a valid Request-URI result and that was my "fix". Without it, when using it with IPv6, the Request-URI was invalid.
Yet what I didn't observe was that other functions (`add_contact_alias()` without parameters and `set_contact_alias()`) always did include the square brackets around the IPv6 in the saved contact alias. So with my extra addition, using the alias there is a doubling of the square brackets. In hindsight making all the alias creating code consistent would've been a better fix, but I simply didn't realize it probably was fine in all other cases, but in mine. Sorry...