Rendezvous with select ... else and "or terminate" not possible - but how do I quit this task?

[Some Dude <john@peppermind.com>]

I have a task with entries Start, Stop, Send, Close and an else clause that does some main processing when none of the entries are processed. So the structure is (very simplified):

task body Connection_Handler is
      Done : Boolean := False;
   begin
      accept Start (Socket : Socket_Type) do
        -- do this first 
      end Start;
      loop
         select when not Done =>
            accept Stop do
               Done := True;
            end Stop;
         or when not Done =>
            accept Send (Socket : Socket_Type; Command : Command_Type) do
               -- do something
            end Send;
         or when not Done =>
            accept Close (Socket : Socket_Type) do
               -- do something
               end Close;
         else
            if not Done then
               -- receive data if necessary using GNAT.sockets.Check_Selector
               -- while no data is sent
            end if;
         end select;
         exit when Done;
      end loop;
   end Connection_Handler;

However, when Stop is called and Done set to True, I get 

  raised TASKING_ERROR : s-tasren.adb:445

as an exception in my AUnit test harness and the test ends prematurely with an error code. This occurs in the main program task, or at least if I add a catch-all exception handler in the above task body, it is *not* triggered there.

I thought this occurs perhaps because there is no terminate alternative, but if I add:
 
   or terminate;

before the else part, I get the error message "else part not allowed with other alternatives". So this is not possible.

Is there a way to stop the task gracefully (without abort) but also do some continuous processing like in the else part? Does anybody have an idea what might cause this error?