client: Warn if -r specified but parcel already checked out
client: Warn if -r specified but parcel already checked out

- If the user specifies --rollback to checkout or resume but the parcel
is already checked out, the --rollback argument is ignored.  Warn the
user in this case.

cmusatyalab/openisr,cmusatyalab/openisr,cmusatyalab/openisr,cmusatyalab/openisr,cmusatyalab/openisr