bug#36810: 26.2; package.el; package-refresh-contents, Bad Request (http over https)

[Eli Zaretskii]

> From: gnu@crabapple.me.uk
> Date: Thu, 25 Jul 2019 17:42:57 +0100
> 
> Replicate with:
> emacs -Q
> M-x package-initialize RET
> M-x set-variable RET debug-on-error RET t RET
> package-refresh-contents
> => Debugger entered--Lisp error: (file-error
> "https://elpa.gnu.org/packages/archive-contents"; "Bad Request")
> 
> In wireshark I observe a TLS1.2 session with elpa.gnu.org, terminated
> from localhost, then another connection established to port 443 on
> elpa.gun.org but no TLS setup and then a straight HTTP GET request (for
> /packages/archive-contents).
> Server responds 400 (Bad Request):
> "Your browser sent a request that this server could not understand.
> Reason: You're speaking plain HTTP to an SSL-enabled server port."

See bug#36749 for a possible solution.