Remove any lingering callbacks for a removed channel, rename an internal method variable
Remove any lingering callbacks for a removed channel, rename an internal method variable

fkarb/pika-python3,hugoxia/pika,renshawbay/pika-python3,vrtsystems/pika,reddec/pika,skftn/pika,Zephor5/pika,benjamin9999/pika,pika/pika,shinji-s/pika,jstnlef/pika,vitaly-krugl/pika,zixiliuyue/pika,knowsis/pika,Tarsbot/pika