run-pipeline: ctrl+c to stop gracefully, ctrl+c again to terminate

[chfoo]

Sometimes users (cough, cough) may have slippy fingers and accidentally ctrl+c the run-pipeline process.

Instead of terminating immediately upon ctrl+c, it could be better to initiate graceful shutdown like touch STOP does. It would print, in addition, a message saying something like "press ctrl+c again to terminate immediately". On accidents, this would give the item a chance to finish for those who are patient.