Fixed regression in 1d55a9f (catch RTSLibNotInCFS)
Fixed regression in 1d55a9f (catch RTSLibNotInCFS)

* An abusive catch of RTSLibNotInCFS in execute_command was retrying the
  command endlessly, which is bad on general principle but even worse
  when the RTSLibNotInCFS is legit and should get through (i.e. trying
  to delete a non-existent MappedLUN would result in and endless loop).

cloud4life/targetcli-fb,agrover/targetcli-fb,Datera/targetcli,Datera/targetcli,cvubrugier/targetcli-fb