readline: fix detection of carriage return

lib/internal/readline/interface.js

@@ -590,6 +590,7 @@ class Interface extends InterfaceConstructor {
       if (this[kLine_buffer]) {
         string = this[kLine_buffer] + string;
         this[kLine_buffer] = null;
+        lineEnding.lastIndex = 0; // Start the search from the beginning of the string.
         newPartContainsEnding = RegExpPrototypeExec(lineEnding, string);
       }
       this[kSawReturnAt] = StringPrototypeEndsWith(string, '\r') ?

test/parallel/test-readline-carriage-return-between-chunks.js

@@ -0,0 +1,23 @@
+'use strict';
+
+const common = require('../common');
+
+const assert = require('node:assert');
+const readline = require('node:readline');
+const { Readable } = require('node:stream');
+
+
+const input = Readable.from((function*() {
+  yield 'a\nb';
+  yield '\r\n';
+})());
+const rl = readline.createInterface({ input, crlfDelay: Infinity });
+let carriageReturns = 0;
+
+rl.on('line', (line) => {
+  if (line.includes('\r')) carriageReturns++;
+});
+
+rl.on('close', common.mustCall(() => {
+  assert.strictEqual(carriageReturns, 0);
+}));