downloads: fixed archive links from file tree view

rhodecode/templates/files/files_browser.mako

@@ -30,7 +30,7 b''
             % if c.enable_downloads:
               <% at_path = '{}.zip'.format(request.GET.get('at') or c.commit.raw_id[:6]) %>
               <div title="${_('Download tree at {}').format(at_path)}" class="btn btn-default new-file">
-                <a href="${h.route_path('repo_archivefile',repo_name=c.repo_name, fname=c.commit.raw_id)}">
+                <a href="${h.route_path('repo_archivefile',repo_name=c.repo_name, fname='{}.zip'.format(c.commit.raw_id))}">
                     ${_('Download tree at {}').format(at_path)}
                 </a>
               </div>