The bug reporting system has worked well for me for more than a decade and I wouldn't want to give it up. But I don't believe that everyone has to agree with me. I don't see any value in requiring that all libraries use the same system. Boost can/should require an issue posting sysyem, but doesn't have to mandate which one. So just shut down the system for coroutine and fiber. Problem solved.
Not really: if a component is missing from Trac, then folks will still submit issues there (under the wrong component), and someone will either have to manually move it to Github, or close it down with an explanation - in which case the reporter may well just go off in a huff rather than re-file in the correct place. I don't care what we use, but it has to be easy to move reports between components, which IMO means some degree of integration. John.