Prepending self node fix

Author: ttk

Tests/HtmlPageCrawlerTest.php

@@ -260,6 +260,10 @@ public function testPrepend()
         $c = new HtmlPageCrawler('<div id="content"></div>');
         $c->filter('#content')->prepend(new HtmlPageCrawler('<p>Text before h1</p><p>and more text before</p>'));
         $this->assertEquals('<div id="content"><p>Text before h1</p><p>and more text before</p></div>', $c->saveHTML());
+
+        $c = new HtmlPageCrawler('<div id="content"><span>Prepend Self</span></div>');
+        $c->filter('#content')->prepend($c->filter('span'));
+        $this->assertEquals('<div id="content"><span>Prepend Self</span></div>', $c->saveHTML());
     }
 
     /**

src/HtmlPageCrawler.php

@@ -483,7 +483,7 @@ public function prepend($content)
                 $newnode = static::importNewnode($newnode, $node, $i);
                 if ($refnode === null) {
                     $node->appendChild($newnode);
-                } else {
+                } else if ($refnode !== $newnode) {
                     $node->insertBefore($newnode, $refnode);
                 }
                 $newnodes[] = $newnode;