[issue22] non-existing deltas/equal diffs

templates/issue.html

 {%extends "base.html"%}
 {%block body%}
 <h2>Issue: {{issue.subject}} {%if issue.closed %} (Closed) {%endif%}</h2>
 
 {%if issue.draft_count%}
 <div class="error">You have <b>{{issue.draft_count}} draft</b>
  comment{{issue.draft_count|pluralize}}.
 Drafts are not viewable by others; use
 <a class="novisit" href="{%url codereview.views.publish issue.key.id%}">
 Publish+Mail Comments</a> ('m') to let others view them.
@@ skipping 88 matching lines @@
     {{patch.num_comments}} comment{{patch.num_comments|pluralize}}
     {%if patch.num_drafts%}<span style="color:red">+
     {{patch.num_drafts}} draft{{patch.num_drafts|pluralize}}</span>
     {%endif%}
   </a>
   {%if patch.num_comments or patch.num_drafts%}</b>{%endif%}
   </td>
   <td>
     {%for other in patchsets%}
       {%ifnotequal other patchset%}
-        <a href="/{{issue.key.id}}/diff2/{{other.key.id}}:{{patchset.key.id}}/{{patch.key.id}}">delta from patch set {{forloop.counter}}</a>
+        {%for opatch in other.patch_set%}
+          {%ifequal opatch.filename patch.filename%}
+            {%ifnotequal opatch.text patch.text%}
+              <a href="/{{issue.key.id}}/diff2/{{other.key.id}}:{{patchset.key.id}}/{{patch.key.id}}">
+              delta from patch set {{forloop.parentloop.counter}}</a>
+            {%endifnotequal%}
+          {%endifequal%}
+        {%endfor%}
       {%endifnotequal%}
     {%endfor%}
   </td>
 </tr>
 {%endfor%}
 </table>
 </div>
 {%endfor%}
 
 {%ifequal user issue.owner%}
@@ skipping 53 matching lines @@
 <a href="javascript:M_hideAllComments('cl', {{messages|length}})">
 Collapse All Comments</a>
 {%endif%}
 
 <script language="JavaScript" type="text/javascript"><!--
 document.onkeypress = function(evt) { return M_changelistKeyPress(evt); }
 // -->
 </script>
 
 {%endblock%}