bug#23620: 25.0.94; url-retrieve fails on localhost

[Paul Eggert]

I'm not observing this problem on my platform (Fedora 23 x86-64, local web 
server is sthttpd).

I do see the problem if I attempt to connect to a non-webserver attached to a 
local TCP port (in my case, port 943 attached to sshd); perhaps your webserver 
isn't set up properly? But that situation looks like Bug#20159, i.e., user error 
not a bug in url-retrieve. Its callbacks are supposed to check status, not 
merely call 'message' willy-nilly.