Fix tag conflict when install plugin

cloudcontrol/node/host/plugins.py

@@ -42,6 +42,8 @@ class Plugin(object):
             err_msg = 'Error during plugin installation (%s): %s' % (
                 self.name, exc)
             logger.exception(err_msg)
+            # make sure all tags are stopped
+            self.tag_db.set_parent(None)
             raise RuntimeError(err_msg)
         else:
             # prevents module from being garbage collected