Activity Search doesn't show link for activities with no subject

In activity search, the only way to view the activity is by clicking the subject. Activities with no subjects have nothing as the link text.

In the template CRM/Contact/Form/Search/Custom/ActivitySearch.tpl, there's actually an attempt to solve this by adding "(no subject)" as the body of the link, but the

{if}

argument isn't working right:

{if $row.activity_subject NEQ "NULL"}

I think Smarty is evaluating it as N-U-L-L "Null" rather than a null value. That means that all activities are assumed to be non-null. I've attached a patch that changes it to:

{if isset($row.activity_subject)}

and it works as intended.