repl: remove obsolete buffer clearing

It is checked if an command buffer exists or not. This code branch
can only be reached if none exist, so there's no need to clear that
buffer again.

PR-URL: https://github.com/nodejs/node/pull/25731
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>

lib/repl.js

@@ -637,7 +637,6 @@ function REPLServer(prompt,
         self.outputStream.write('npm should be run outside of the ' +
                                 'node repl, in your normal shell.\n' +
                                 '(Press Control-D to exit.)\n');
-        self.clearBufferedCommand();
         self.displayPrompt();
         return;
       }