prefer threadsafe sleep here

Author: busterb

modules/exploits/multi/handler.rb

@@ -57,7 +57,7 @@ def exploit
     loop do
       break if session_created? && datastore['ExitOnSession']
       break if timeout > 0 && (stime + timeout < Time.now.to_f)
-      sleep(1)
+      Rex::ThreadSafe.sleep(1)
     end
   end
 end