Issue #1575060 by Spleshka, andypost, serm, mcjim, nod_: Fixed ajax_h…

…tml_ids() are broken for forms with file element (encoding=multipart/form-data).

includes/common.inc

@@ -3878,7 +3878,16 @@ function drupal_html_id($id) {
       // requested id. $_POST['ajax_html_ids'] contains the ids as they were
       // returned by this function, potentially with the appended counter, so
       // we parse that to reconstruct the $seen_ids array.
-      foreach ($_POST['ajax_html_ids'] as $seen_id) {
+      if (is_array($_POST['ajax_html_ids'])) {
+        $ajax_html_ids = $_POST['ajax_html_ids'];
+      }
+      else {
+        // jquery.form.js may send the server a comma-separated string instead
+        // of an array (see http://drupal.org/node/1575060), so we need to
+        // convert it to an array in that case.
+        $ajax_html_ids = explode(',', $_POST['ajax_html_ids']);
+      }
+      foreach ($ajax_html_ids as $seen_id) {
         // We rely on '--' being used solely for separating a base id from the
         // counter, which this function ensures when returning an id.
         $parts = explode('--', $seen_id, 2);