This may have broken with the introduction of _mongoc_client_command_append_iterator_opts_to_command:
https://evergreen.mongodb.com/task/mongo_c_driver_gcc46_test_2.4_server_noauth_sasl_nossl_8095e0274c27e3d7df455eb4adadef76fded4b8b_16_10_20_00_20_55