qa-fiberassign reports assignments >6mm from positioner

Track down why qa-fiberassign is reporting assignments more than 6mm from the positioner center. It is likely a bookkeeping problem on the qa-fiberassign side, but we need to make sure that the assignments are correct.

Start with the qa-fiberassign entry point and reproduce the report of assignments more than 6 mm from the positioner center. Trace how assignments and positioner centers are recorded and compared; the work is done when the bookkeeping issue is identified and qa-fiberassign confirms that assignments are correct.

Written by the indexing model from the issue text.