Tweak new dispatcher error handling so that the default errback is called if a custom errback raises an error (@jerith).
Tweak new dispatcher error handling so that the default errback is called if a custom errback raises an error (@jerith).

vishwaprakashmishra/xmatrix,harrissoerja/vumi,TouK/vumi,harrissoerja/vumi,vishwaprakashmishra/xmatrix,TouK/vumi,TouK/vumi,harrissoerja/vumi,vishwaprakashmishra/xmatrix