If a job with more than one opcodes is being processed, and the master
daemon crashes between two opcodes, we have the first N opcodes marked
successful, and the rest marked as queued. This means that the overall
jbo status is queued, and thus on master daemon restart it will be
resent for completion.

However, the RunTask() function in jqueue.py doesn't deal with
partially-completed jobs. This patch makes it simply skip such opcodes.

An alternative option would be to not mark partially-completed jobs as
QUEUED but instead RUNNING, which would result in aborting of the job at
restart time.

Signed-off-by: Iustin Pop <iustin@google.com>
Reviewed-by: Guido Trotter <ultrotter@google.com>