Grants are lost on node save

Using Drupal 7 version 7.39 when I save a node the users that have access to this node disappear from the grant tab.
I checked and the access is removed from node_access and nodeaccess tables.
I realize that the nodeaccess function nodeaccess_delete_user_reference it's called in the process. Inside this function user_load_multiple is called with a null value as parameter. In this case, user_load_multiple is returning all the users.
I did a small patch to overcome this. The path is also fixing the original problem of losing the data from the access tables.