when they're preempting another GPU job.
The problem was as follows:
- job A is chosen to preempt job B
- we tell job B to quit, and initialize job A but don't start it;
however, we set if scheduler state to SCHEDULED
(rather than UNINITIALIZED)
- job B exits, and we start job A.
Since its state is not UNITIALIZED, we don't set up its slot dir.
- job A runs in an empty slot dir, doesn't find its files, and bombs out.
- client: add <slot_debug> option (prints messages about
allocation of slots, creating/removing files in slot dirs).
svn path=/trunk/boinc/; revision=18217