serf: refactor the hasAliveMembers check
serf: refactor the hasAliveMembers check

patrickviet/serf,jmptrader/serf,pmenglund/serf,yonglehou/serf,minhkiller/serf,mbrukman/serf,minhkiller/serf,pmenglund/serf,jmptrader/serf,mapuri/serf,pmenglund/serf,hashicorp/serf,dalehamel/serf,curtiszimmerman/serf,FollowMyDev/serf,dalehamel/serf,FollowMyDev/serf,patrickviet/serf,mbrukman/serf,jmptrader/serf,mapuri/serf,hashicorp/serf,hashicorp/serf,gnawhleinad/serf,yonglehou/serf,curtiszimmerman/serf,gnawhleinad/serf,FollowMyDev/serf,dalehamel/serf,FollowMyDev/serf,mbrukman/serf,samaitra/serf,FollowMyDev/serf,minhkiller/serf,FollowMyDev/serf,patrickviet/serf,samaitra/serf,dalehamel/serf,mapuri/serf,dalehamel/serf,hashicorp/serf,patrickviet/serf,gnawhleinad/serf,pmenglund/serf,minhkiller/serf,yonglehou/serf,samaitra/serf,jmptrader/serf,minhkiller/serf,jmptrader/serf,gnawhleinad/serf,gnawhleinad/serf,pmenglund/serf,curtiszimmerman/serf,samaitra/serf,mbrukman/serf,samaitra/serf,patrickviet/serf,mbrukman/serf,minhkiller/serf,yonglehou/serf,samaitra/serf,dalehamel/serf,patrickviet/serf,gnawhleinad/serf,hashicorp/serf,mbrukman/serf,curtiszimmerman/serf,yonglehou/serf,jmptrader/serf,curtiszimmerman/serf,pmenglund/serf,mapuri/serf,mapuri/serf,curtiszimmerman/serf,mapuri/serf,yonglehou/serf