If the handler doesn't return anything we need to handle that

tools/httpd_sim.py

@@ -304,6 +304,7 @@ class Handler(SimpleHTTPRequestHandler):
             pieces = cmd.split(" ")
             handler = self.get_parsers().get(pieces[0])
             result = handler(pieces)
+            if(result is not None):
                 response.extend(result)
                 response.extend(b"\n")
         return response