repl: handle buffered string logic on finish

Looks like `clearBufferedCommand` will be called on almost all flows.
Hence history was broken.

PR-URL: nodejs#24389
Fixes: nodejs#24385
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>

lib/readline.js

@@ -348,9 +348,9 @@ Interface.prototype.undoHistory = function() {
 
 // If it's a multiline code, then add history
 // accordingly.
-Interface.prototype.multilineHistory = function() {
-  // check if we got a multiline code
-  if (this.multiline !== '' && this.terminal) {
+Interface.prototype.multilineHistory = function(clearBuffer) {
+  // if not clear buffer, add multiline history
+  if (!clearBuffer && this.terminal) {
     const dupIndex = this.history.indexOf(this.multiline);
     if (dupIndex !== -1) this.history.splice(dupIndex, 1);
     // Remove the last entered line as multiline

lib/repl.js

@@ -667,6 +667,13 @@ function REPLServer(prompt,
         }
       }
 
+      // handle multiline history
+      if (self[kBufferedCommandSymbol].length)
+        REPLServer.super_.prototype.multilineHistory.call(self, false);
+      else {
+        REPLServer.super_.prototype.multilineHistory.call(self, true);
+      }
+
       // Clear buffer if no SyntaxErrors
       self.clearBufferedCommand();
       sawCtrlD = false;
@@ -773,7 +780,6 @@ exports.start = function(prompt,
 
 REPLServer.prototype.clearBufferedCommand = function clearBufferedCommand() {
   this[kBufferedCommandSymbol] = '';
-  REPLServer.super_.prototype.multilineHistory.call(this);
 };
 
 REPLServer.prototype.close = function close() {