Block structures are meant to be an optimization for the LMS, meaning
that they should always be collecting from the published branch of
modulestore. This is what happens by default when it's run from the LMS
celery process, but this code is sometimes invoked from a Studio worker
(e.g. development mode celery, running in immediate in-proc mode).
---------
Co-authored-by: Peter Pinch <pdpinch@mit.edu>
51ac947caf