Log Message:
pbulk-0.63:
Introduce a separate client-prepare script. The default configuration
runs the renamed client_prepare_action for each scan/build client once,
dropping duplicates in the list. Clients are prepared in parallel, but
the master waits for all before starting the actual scan. Make
bulkbuild-restart re-prepare the clients, i.e. in case they have a
pkgsrc tree in a local tmpfs.