Revert "mux_broker_test.go: make non blocking errChan"
Revert "mux_broker_test.go: make non blocking errChan"

This reverts commit d9e32d437cfff8764ac0b9682d1fe3796e57be06. It turns out that it was already non-blocking with a length of one.

grubernaut/packer,grubernaut/packer,dave2/packer,youhong316/packer,mkuzmin/packer,dave2/packer,timsutton/packer,mkuzmin/packer,pecigonzalo/packer,youhong316/packer,mitchellh/packer,hashicorp/packer,rnaveiras/packer,ricardclau/packer,dave2/packer,mitchellh/packer,timsutton/packer,timsutton/packer,bryson/packer,tas50/packer,rnaveiras/packer,dave2/packer,pecigonzalo/packer,mkuzmin/packer,paulmey/packer,paulmey/packer,hashicorp/packer,ricardclau/packer,grubernaut/packer,rnaveiras/packer,bryson/packer,rnaveiras/packer,dave2/packer,tas50/packer,tas50/packer,hashicorp/packer,grubernaut/packer,dave2/packer,paulmey/packer,bryson/packer,paulmey/packer,mkuzmin/packer,timsutton/packer,mitchellh/packer,timsutton/packer,mkuzmin/packer,pecigonzalo/packer,ricardclau/packer,bryson/packer,ricardclau/packer,youhong316/packer,rnaveiras/packer,youhong316/packer,timsutton/packer,hashicorp/packer,ricardclau/packer,mitchellh/packer,youhong316/packer,ricardclau/packer,paulmey/packer,tas50/packer,mitchellh/packer,pecigonzalo/packer,rnaveiras/packer,grubernaut/packer,mkuzmin/packer,youhong316/packer,grubernaut/packer,paulmey/packer,tas50/packer,bryson/packer,bryson/packer,tas50/packer