Should be three commits - ach. But improvements are:-
A change to batch processing that search api tests seem to need so safe to keep here.
Moving the index to a method so that search_api_solr can ensure indexing (another PR over there overrides this method) gets rid of the cache clear that was just needed for sorl
Some checks on the search block that I wrote trying to reproduce the caching issue, might as well keep them
Should be three commits - ach. But improvements are:-