Re: url-retrieve & Emacs 25.2

[Juliusz Chroboczek <jch@irif.fr>]

> With a local http server listening on 127.0.0.1:PORT, `url-retrieve'
> fails to open connections on "http://localhost:PORT" with the following
> error:

> (:error (error connection-failed failed with code 111
>  :host localhost :service 3000))

> However, connections to "http://127.0.0.1:PORT" work fine.

I suspect that your server is listening on IPv4 only, while Emacs
believes that "localhost" works for both IPv6 and IPv4.  (Check the
contents of /etc/hosts -- is there an IPv6 entry for localhost?)

> I cannot reproduce the problem on master where connections to localhost
> work fine (curl and browser connections also work fine).

Master tries all addresses, where Emacs 25 would try only the first one
(the IPv6 one in your case).  That's bug 17976.

-- Juliusz