fix retryWrite bug

Author: HanaPearlman

lib/core/sdam/topology.js

@@ -930,7 +930,8 @@ function executeWriteOperation(args, options, callback) {
     !!options.retryWrites &&
     options.session &&
     isRetryableWritesSupported(topology) &&
-    !options.session.inTransaction();
+    !options.session.inTransaction() &&
+    options.explain === undefined;
 
   topology.selectServer(writableServerSelector(), options, (err, server) => {
     if (err) {

lib/core/topologies/mongos.js

@@ -919,7 +919,8 @@ function executeWriteOperation(args, options, callback) {
     !!options.retryWrites &&
     options.session &&
     isRetryableWritesSupported(self) &&
-    !options.session.inTransaction();
+    !options.session.inTransaction() &&
+    options.explain === undefined;
 
   const handler = (err, result) => {
     if (!err) return callback(null, result);

lib/core/topologies/replset.js

@@ -1188,7 +1188,8 @@ function executeWriteOperation(args, options, callback) {
     !!options.retryWrites &&
     options.session &&
     isRetryableWritesSupported(self) &&
-    !options.session.inTransaction();
+    !options.session.inTransaction() &&
+    options.explain === undefined;
 
   if (!self.s.replicaSetState.hasPrimary()) {
     if (self.s.disconnectHandler) {