handle more than one line of macros in threaded shells

IPython/Shell.py

@@ -415,7 +415,7 b' class MTInteractiveShell(InteractiveShell):'
         if (self.worker_ident is None
             or self.worker_ident == thread.get_ident() ):
             InteractiveShell.runcode(self,code)
-            return
+            return False
 
         # Case 3
         # Store code in queue, so the execution thread can handle it.