client: Always fetch fresh metadata before hoarding
client: Always fetch fresh metadata before hoarding

- Eliminate the parcel-already-checked-out case for "isr hoard".  That is,
always retrieve a new parcel.cfg from the server and a new keyring from the
server or the hoard cache.  This eliminates races in which the parcel
becomes no longer checked out (via "isr ci" or "isr clean") while hoarding
is in progress.

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