Allow batch view to disable the Execute button in some cases.

Although this only disables the UI button element, it doesn't really
prevent anything beyond that...

tailbone/templates/batch/crud.mako

@@ -70,7 +70,7 @@
       % endif
       % if not batch.executed and request.has_perm('{0}.execute'.format(permission_prefix)):
           ## ${h.link_to(execute_title, url('{0}.execute'.format(route_prefix), uuid=batch.uuid))}
-          <button type="button" onclick="location.href = '${url('{0}.execute'.format(route_prefix), uuid=batch.uuid)}';">${execute_title}</button>
+          <button type="button" onclick="location.href = '${url('{0}.execute'.format(route_prefix), uuid=batch.uuid)}';"${'' if execute_enabled else ' disabled="disabled"'}">${execute_title}</button>
       % endif
     </div>
 </%def>

tailbone/views/batch.py

@@ -473,6 +473,7 @@ class BatchCrud(BaseCrud):
             'batch_display': self.batch_display,
             'batch_display_plural': self.batch_display_plural,
             'execute_title': self.handler.get_execute_title(batch),
+            'execute_enabled': True,
             'route_prefix': self.route_prefix,
             'permission_prefix': self.permission_prefix,
             }