Add debug handler for request

Signed-off-by: alex-ak1 <alex_ak1@mail.ru>

Author: alex-ak1

prometheus_client/exposition.py

@@ -226,10 +226,10 @@ class TmpServer(ThreadingWSGIServer):
 
     TmpServer.address_family, addr = _get_best_family(addr, port)
     app = make_wsgi_app(registry)
-    handler = _SilentHandler    # type: WSGIRequestHandler
     if debug:
-        handler = _PrintHandler
-    httpd = make_server(addr, port, app, TmpServer, handler_class=handler)
+        httpd = make_server(addr, port, app, TmpServer, handler_class=_PrintHandler)
+    else:
+        httpd = make_server(addr, port, app, TmpServer, handler_class=_SilentHandler)
     if certfile and keyfile:
         context = _get_ssl_ctx(certfile, keyfile, protocol, client_cafile, client_capath, client_auth_required)
         httpd.socket = context.wrap_socket(httpd.socket, server_side=True)