refactor: simplify multicast route addition in 'attach'
refactor: simplify multicast route addition in 'attach'

dpw/weave,awanke/weave,paulbellamy/weave,tomwilkie/weave,inercia/weave,squaremo/weave,philipz/weave,OnePaaS/weave,beni55/weave,tomwilkie/weave,Lawouach/weave,2opremio/weave,bboreham/weave,inercia/weave,weaveworks/weave,narry/weave,BWITS/weave,bboreham/weave,squaremo/weave,ycaihua/weave,rade/weave,philipz/weave,awh/weave,awanke/weave,19hz/weave,aaam/weave,kidaa/weave,inercia/weave,OnePaaS/weave,kidaa/weave,ycaihua/weave,kidaa/weave,achanda/weave,n054/weave,philipz/weave,n054/weave,rade/weave,bboreham/weave,weaveworks/weave,awanke/weave,OnePaaS/weave,dpw/weave,awh/weave,philipz/weave,n054/weave,errordeveloper/weave,2opremio/weave,cgvarela/weave,2opremio/weave,cgvarela/weave,philipz/weave,rade/weave,aaam/weave,errordeveloper/weave,squaremo/weave,ycaihua/weave,19hz/weave,2opremio/weave,tomwilkie/weave,BWITS/weave,19hz/weave,kidaa/weave,19hz/weave,dpw/weave,rade/weave,paladin74/weave,beni55/weave,achanda/weave,ycaihua/weave,Lawouach/weave,weaveworks/weave,errordeveloper/weave,weaveworks/weave,paladin74/weave,BWITS/weave,inercia/weave,squaremo/weave,dpw/weave,aaam/weave,squaremo/weave,achanda/weave,errordeveloper/weave,BWITS/weave,2opremio/weave,achanda/weave,ycaihua/weave,awh/weave,bboreham/weave,beni55/weave,narry/weave,tomwilkie/weave,Lawouach/weave,n054/weave,aaam/weave,paladin74/weave,Lawouach/weave,narry/weave,awanke/weave,tomwilkie/weave,paulbellamy/weave,cgvarela/weave,cgvarela/weave,paulbellamy/weave,awanke/weave,beni55/weave,aaam/weave,awh/weave,rade/weave,bboreham/weave,dpw/weave,errordeveloper/weave,inercia/weave,BWITS/weave,OnePaaS/weave,narry/weave,cgvarela/weave,narry/weave,awh/weave,achanda/weave,paladin74/weave,kidaa/weave,paulbellamy/weave,beni55/weave,n054/weave,OnePaaS/weave,paladin74/weave