sanger/sequencescape — pull request #492 by mattdenner (2012-05-06 09:36:03+00:00)
Title: 25247387 mismatch in submission next requests when separated over batches

Sometimes a submission, particularly in the case of library creation,
can go through pipelines in several batches. If these batches then
cause requests to be created (for example, failing a sequencing batch
does) then the request graph for a submission can change and the
behaviour of Submission#next_request is not guaranteed.

This commit changes that so that it works with the original part of the
request graph based on the orders of a submission.