tools/dc: fix error introduced by #2369 (#2370)
tools/dc: fix error introduced by #2369 (#2370)

Since we shift away the first arg we should use the local variable.
netsec-ethz/scion,netsec-ethz/scion,netsec-ethz/scion,netsec-ethz/scion,Oncilla/scion,Oncilla/scion,Oncilla/scion,Oncilla/scion