Reverse on :db/isComponent attributes has a special case for reading.

Fixes a 'bug' where RichEntity.read can not be used for reversed attributes that are components, due to an undocumented special case in datomic.Entity.get. Datomisca is expecting a collection but receives a single entity response, and throws an exception.
We've run in to this issue a few times, and had to drop down to using Entity.getAs.

Refer:
 - https://groups.google.com/forum/#!searchin/datomic/reverse$20get/datomic/Eu7l__rA-xk/MWqTTECbJI0J