State reasons from previous run not cleared

[Tim Waugh]

The hp backend does not initially clear state reasons it manages.

If state reasons were set in a previous run, they will still be present unless we clear them.

[Tim Waugh (twaugh)]

Here's a patch to fix it.

[David Suffield (david-suffield)]

Thanks, I applied a similar patch that did not force a status check (ie: loop_test) before each print job.