py9p: do not clunk authfs fids (koska there is no "open")

maybe it is better to open it previously, but it should be investigated

py9p/py9p.py

@@ -1044,7 +1044,7 @@ def tclunk(self, req):
         req.fid = req.sock.getfid(req.ifcall.fid)
         if not req.fid:
             return self.respond(req, Eunknownfid)
-        if hasattr(self.fs, 'clunk'):
+        if hasattr(self.fs, 'clunk') and not (req.fid.qid.type & QTAUTH):
             self.fs.clunk(self, req)
         else:
             self.respond(req, None)