Melpa upgrade ignores url-proxy-service

Question

I use Emacs in a corporate environment behind a proxy.

I have customized url-proxy-services:

 '(url-proxy-services
   (quote
    (("http" . "proxy:3128")
     ("https" . "proxy:3128"))))

I use the package tool:

(require 'package)

And I have customized the Melpa archives:

 '(package-archives (quote (("melpa" . "http://melpa.org/packages/"))))

When I run package-list-packages I see the packages and the list gets updated. This means the proxy gets used for this.

But when I try to install a package, Emacs stalls:

Importing package-keyring.gpg...done
Package refresh done
2 packages can be upgraded; type ‘U’ to mark them for upgrading.
2 packages marked for upgrading.
Upgrade these 2 packages (groovy-mode-2.0, s-1.12.0)? y
Package menu: Operation started [Upgrading 2]
Contacting host: melpa.org:80
Quit

When I sniff the network with tcpdump, I can see packets send directly to some hosts on port 80. This matches the last message "Contacting host: melpa.org:80".

Why does Melpa ignore the proxy for the download? And how can I change this?

Answer 1

This is probably a bug in version 26. I just compiled 27 and it works as expected.