Issue #421294 by superspring: Fixed non-ascii character in function theme_user_signature()().

core/modules/user/user.module

@@ -1693,7 +1693,7 @@ function theme_user_signature($variables) {
 
   if ($signature) {
     $output .= '<div class="clear">';
-    $output .= '<div>—</div>';
+    $output .= '<div>&mdash;</div>';
     $output .= $signature;
     $output .= '</div>';
   }