While testing, show printerd output for failed tests.
File output device now accepts "wait" option for testing.

e.g. file:///tmp/foo?wait=5

It will sleep for the specified number of seconds before processing
input.
New test case: job3.

This sends a job through the file backend with a delay of 1s.

The point of this test is to make sure the filter pipeline is set up
and run correctly.
Don't start running filters when the job state changes to PROCESSING.

Let the engine take care of that.
Whitespace only.
Set pending_job_state before starting processes.