比如：
(display-buffer (url-retrieve-synchronously "http://example.com"))
接收的信息：
HTTP/1.1 200 OK
Content-Encoding: gzip
Accept-Ranges: bytes
Cache-Control: max-age=604800
Content-Type: text/html; charset=UTF-8
Date: Mon, 27 May 2019 14:37:04 GMT
Etag: "1541025663"
Expires: Mon, 03 Jun 2019 14:37:04 GMT
Last-Modified: Fri, 09 Aug 2013 23:54:35 GMT
Server: ECS (oxr/830F)
Vary: Accept-Encoding
X-Cache: HIT
Content-Length: 606
<!doctype html>
<html>
...
</html>
现在需要解析 Body（即上面的 HTML 文档），原来我一直用 url-http-end-of-headers：
(with-current-buffer (url-retrieve-synchronously "http://example.com")
(display-buffer (current-buffer))
(goto-char url-http-end-of-headers))
现在突然发现当 Cache 开着的时候，url-http-end-of-headers 就不管用了，参见 Bug#35927。目测 (re-search-forward "^$") 能解决这个问题，好奇大家是怎么解决的？对这 "^$" 不是很确定。