panic: ./mesos-dns flag redefined: log_dir

[f1-outsourcing]

./mesos-dns flag redefined: log_dir
panic: ./mesos-dns flag redefined: log_dir

goroutine 1 [running]:
flag.(*FlagSet).Var(0xc0000622a0, 0x8f8c40, 0xc00001ef50, 0x88b721, 0x7, 0x89c8c8, 0x2f)
/usr/lib/golang/src/flag/flag.go:805 +0x529
flag.(*FlagSet).StringVar(0xc0000622a0, 0xc00001ef50, 0x88b721, 0x7, 0x0, 0x0, 0x89c8c8, 0x2f)
/usr/lib/golang/src/flag/flag.go:708 +0x8a
flag.(*FlagSet).String(0xc0000622a0, 0x88b721, 0x7, 0x0, 0x0, 0x89c8c8, 0x2f, 0xc00001ef40)
/usr/lib/golang/src/flag/flag.go:721 +0x8b
flag.String(0x88b721, 0x7, 0x0, 0x0, 0x89c8c8, 0x2f, 0x1a)
/usr/lib/golang/src/flag/flag.go:728 +0x69