Index: src/wp-login.php
===================================================================
--- src/wp-login.php	(revision 45003)
+++ src/wp-login.php	(working copy)
@@ -638,6 +638,11 @@
 
 		<?php
 		login_footer( 'user_login' );
+		?>
+		<script type="text/javascript">
+		document.getElementById('wp-submit').addEventListener('click',function(){this.form.submit();this.disabled=true;});
+		</script>
+		<?php
 
 		break;