When using http protocol to access, nginx will respond with 400 and
report "400 The plain HTTP request was sent to HTTPS port".
The reason is that http 497 error[1] appeared in nginx, so 497
error was redirected to https protocol.
[1] 56f5331683/src/http/ngx_http_special_response.c (L274)
Change-Id: I01c35318dd5d219dbb31e6a89bdc05d2a4db7804