Upstream sent duplicate header line

Hi team, When using discopower I notice the following in the logs when looking at disco.php. On both dev-master and latest release.

2024/08/21 03:28:41 [warn] 286#286: *4918 upstream sent duplicate header line: "Date: Wed, 21 Aug 2024 03:28:41 GMT", previous value: "Date: Wed, 21 Aug 2024 03:28:41 GMT", ignored while reading response header from upstream, client: x.x.x.x, server: x.x.x.x, request: "GET /simplesaml/module.php/discopower/disco.php?entityID=https%3A%2F%2Fx.x.x.x%2Fsimplesaml%2Fmodule.php%2Fsaml%2Fsp%2Fmetadata.php%2Fdefault-sp&return=https%3A%2F%2Fx.x.x.x%2Fsimplesaml%2Fmodule.php%2Fsaml%2Fsp%2FdiscoResponse%3FAuthID%3D_889a13be559c3295def3f9745d42df88a4d1fd33ca%253Ahttps%253A%252F%252Fx.x.x.x%252Fsimplesaml%252Fmodule.php%252Fsaml%252Fsp%252Flogin%252Fdefault-sp%253FReturnTo%253Dhttps%25253A%25252F%25252Fx.x.x.x%25252F%25253Fs%25253Dupload&returnIDParam=idpentityid HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "x.x.x.x", referrer: "https://x.x.x.x"

The rest of SSP seems to not have this problem.

首先，针对 dev-master 和最新发布版本重现对 module.php/discopower/disco.php 的 GET 请求，同时检查响应头和 nginx 日志。跟踪重复的 Date 响应头在哪里生成；完成的标准是：请求不再发出重复的 Date 响应头，同时不影响 SSP 的其余部分。