GODRIVER-1487 fix adding UnknownTransactionCommitResult (#307)

Author: iwysiu

x/mongo/driver/errors.go

@@ -15,6 +15,9 @@ var (
 	nodeIsRecoveringCodes   = []int32{11600, 11602, 13436, 189, 91}
 	notMasterCodes          = []int32{10107, 13435}
 	nodeIsShuttingDownCodes = []int32{11600, 91}
+
+	unknownReplWriteConcernCode   = int32(79)
+	unsatisfiableWriteConcernCode = int32(100)
 )
 
 var (

x/mongo/driver/operation.go

@@ -432,8 +432,10 @@ func (op Operation) Execute(ctx context.Context, scratch []byte) error {
 					Code:    int32(tt.WriteConcernError.Code),
 					Message: tt.WriteConcernError.Message,
 				}
-				if err.Code == 64 || err.Code == 50 || tt.WriteConcernError.Retryable() {
-					err.Labels = []string{UnknownTransactionCommitResult}
+				// The UnknownTransactionCommitResult label is added to all writeConcernErrors besides unknownReplWriteConcernCode
+				// and unsatisfiableWriteConcernCode
+				if err.Code != unknownReplWriteConcernCode && err.Code != unsatisfiableWriteConcernCode {
+					err.Labels = append(err.Labels, UnknownTransactionCommitResult)
 				}
 				return err
 			}