serf: only try to persist tags if a tags file is configured
serf: only try to persist tags if a tags file is configured

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