mongodb/mongo-c-driver — pull request #147 by bjori (2014-12-23 18:55:18+00:00)
Title: CDRIVER-492: Report WriteConcern error on writes

Renamed the field, and fixed the failure check.
There can only ever be one WriteConcernError, which is a bson object
containing the code (int), errInfo (object) and errmsg (cstring),
so there is no arrays to merge.