clean last exception to prevent printing TB

( #1629 )

src/common/xmpp/transports_nb.py

@@ -209,6 +209,7 @@ class NonBlockingTcp(PlugIn, IdleObject):
 		except Exception, e:
 			if len(e.args)  > 0 and isinstance(e.args[0], int):
 				errnum = e[0]
+			sys.exc_clear()
 			# "received" will be empty anyhow 
 		if errnum == socket.SSL_ERROR_WANT_READ:
 			pass