bug#12893: 24.2.50; url-retrieve fails for localhost

[Dmitry Gutov <dgutov@yandex.ru>]

I have an HTTP server running, started from an inferior process.

If I evaluate (switch-to-buffer (url-retrieve-synchronously
"http://localhost:24959/classes")), it brings me to an empty buffer
which has "failed" in the mode line.

If I call the asynchronous version, it passes this into the callback:

((:error (error connection-failed failed with code 111
 :host localhost :service 24959)))

Strangely, it works if I replace "localhost" with "127.0.0.1" or even
"localhost.localdomain". But neither Firefox nor curl have a problem
with reading from the first version of the URL.

In GNU Emacs 24.2.50.1 (x86_64-unknown-linux-gnu, GTK+ Version 3.6.0)
 of 2012-11-15 on vbx
Bzr revision: 110872 rgm@gnu.org-20121115061756-ncyfcon4pkq7ku57
Windowing system distributor `The X.Org Foundation', version 11.0.11300000
System Description:	Ubuntu 12.10

Important settings:
  value of $LC_MONETARY: en_US.UTF-8
  value of $LC_NUMERIC: en_US.UTF-8
  value of $LC_TIME: en_US.UTF-8
  value of $LANG: en_US.UTF-8
  locale-coding-system: utf-8-unix
  default enable-multibyte-characters: t

Major mode: Emacs-Lisp

Minor modes in effect:
  recentf-mode: t
  shell-dirtrack-mode: t
  helm-match-plugin-mode: t
  elisp-slime-nav-mode: t
  paredit-mode: t
  global-undo-tree-mode: t
  undo-tree-mode: t
  global-diff-hl-mode: t
  diff-hl-mode: t
  diff-auto-refine-mode: t
  savehist-mode: t
  yas-global-mode: t
  yas-minor-mode: t
  global-auto-revert-mode: t
  autopair-global-mode: t
  cua-mode: t
  winner-mode: t
  ido-ubiquitous-mode: t
  ido-everywhere: t
  show-paren-mode: t
  global-ethan-wspace-mode: t
  ethan-wspace-mode: t
  ethan-wspace-clean-many-nls-eof-mode: t
  ethan-wspace-clean-no-nl-eof-mode: t
  ethan-wspace-clean-eol-mode: t
  ethan-wspace-clean-tabs-mode: t
  eproject-mode: t
  eldoc-mode: t
  mouse-wheel-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  column-number-mode: t
  line-number-mode: t
  auto-fill-function: do-auto-fill
  transient-mark-mode: t

Recent input:
<M-return> <M-return> <down-mouse-1> <mouse-1> <down-mouse-1> 
<mouse-1> <M-return> C-x C-g C-x C-g C-; g e m f <return> 
M-: <up> <up> <up> <up> <up> <up> <up> <up> <up> <up> 
<up> <up> <up> <up> <up> <up> <up> <up> <up> <up> <up> 
<up> <up> <up> <up> <up> <up> <up> <up> <down> <return> 
<up> <end> <home> q M-x r v m <return> M-: <up> <up> 
<down> <return> <help-echo> <down-mouse-1> <mouse-movement> 
<mouse-1> M-x z o s s i m a <return> M-x z o s s i 
m a - j u m p <return> <down> M-x <return> C-g M-x 
f i n d - l i b <return> z o s s i m a <return> <up> 
<left> <left> <left> <left> <left> <C-backspace> <C-backspace> 
<C-backspace> <C-backspace> <C-backspace> <C-backspace> 
<C-backspace> l o c a l h o s t C-M-x C-x C-s <C-tab> 
M-. <up> <up> M-. <C-tab> <help-echo> <help-echo> M-x 
r e <return>

Recent messages:
zossima.el [Gemfile] -scratch-
Contacting host: localhost:24959
save-current-buffer: Search failed: "

"
Contacting host: localhost:24959
save-current-buffer: Search failed: "

"
Gemfile [zossima.el] -scratch-

Load-path shadows:
/home/gutov/.emacs.d/site-lisp/smartrep.el/smartrep hides ~/.emacs.d/site-lisp/smartrep
/home/gutov/.emacs.d/elpa/magit-20121014.1043/.dir-locals hides /home/gutov/emacs-bzr/emacs-24/lisp/gnus/.dir-locals

Features:
(shadow sort mail-extr emacsbug message rfc822 mml mml-sec mm-decode
mm-bodies mm-encode mailabbrev gmm-utils mailheader sendmail mule-util
find-func mail-utils network-stream starttls url-cache url-http tls
mail-parse rfc2231 rfc2047 rfc2045 ietf-drums url-gw url-auth zossima
url url-proxy url-privacy url-expand url-methods url-history url-cookie
url-domsuf url-util mailcap json rvm debug unsafep flymake-ruby
flymake-easy flymake ruby-electric ruby-tools subword inf-ruby ruby-mode
helm-misc tramp-cache tramp-sh recentf tree-widget wid-edit bow
helm-files image-dired tramp tramp-compat tramp-loaddefs shell pcomplete
format-spec dired-x dired-aux thingatpt helm-tags helm-locate helm-help
helm-external helm-bookmark helm-buffers helm-grep helm-regexp grep
helm-elscreen helm-utils compile helm-match-plugin helm helm-config
elisp-slime-nav etags paredit saveplace win-switch undo-tree diff
diff-hl smartrep face-remap vc-hg vc-git vc-dir ewoc vc vc-dispatcher
diff-mode savehist yasnippet autorevert autopair cua-base winner
point-stack .emacs-loaddefs server auto-complete-autoloads
autopair-autoloads clojure-mode-autoloads coffee-mode-autoloads
expand-region-autoloads flymake-coffee-autoloads flymake-ruby-autoloads
flymake-easy-autoloads helm-descbinds-autoloads iedit-autoloads
iy-go-to-char-autoloads markdown-mode-autoloads move-text-autoloads
popup-autoloads rainbow-mode-autoloads ruby-electric-autoloads
ruby-tools-autoloads rvm-autoloads sass-mode-autoloads lisp-mnt
finder-inf starter-kit-bindings-autoloads windmove
starter-kit-lisp-autoloads elisp-slime-nav-autoloads
starter-kit-autoloads smex starter-kit-misc warnings ffap url-parse
auth-source eieio byte-opt bytecomp byte-compile cconv gnus-util mm-util
mail-prsvr password-cache url-vars ido-ubiquitous ido paren
starter-kit-defuns uniquify magit-autoloads ido-ubiquitous-autoloads
smex-autoloads find-file-in-project-autoloads
idle-highlight-mode-autoloads paredit-autoloads switch-window-autoloads
typing-autoloads undo-tree-autoloads wgrep-autoloads
win-switch-autoloads yaml-mode-autoloads yasnippet-autoloads
zossima-autoloads inf-ruby-autoloads package devenv eproject-extras
ibuf-macs ibuf-ext ibuffer iswitchb ethan-wspace eproject derived
easy-mmode esh-var esh-io esh-cmd esh-opt esh-ext esh-proc esh-arg eldoc
esh-groups eshell esh-module esh-mode esh-util progmodes mmm mmm-auto
mmm-vars mmm-compat cl-macs gv cl keys quail help-mode easymenu hippie
hippie-exp comint ansi-color dired winring ring transpose-frame iflipb
misc prefs help-at-pt cus-start cus-load edmacro kmacro defuns advice
help-fns cl-lib advice-preload time-date tooltip ediff-hook vc-hooks
lisp-float-type mwheel x-win x-dnd tool-bar dnd fontset image regexp-opt
fringe tabulated-list newcomment lisp-mode register page menu-bar
rfn-eshadow timer select scroll-bar mouse jit-lock font-lock syntax
facemenu font-core frame cham georgian utf-8-lang misc-lang vietnamese
tibetan thai tai-viet lao korean japanese hebrew greek romanian slovak
czech european ethiopic indian cyrillic chinese case-table epa-hook
jka-cmpr-hook help simple abbrev minibuffer loaddefs button faces
cus-face macroexp files text-properties overlay sha1 md5 base64 format
env code-pages mule custom widget hashtable-print-readable backquote
make-network-process dbusbind dynamic-setting system-font-setting
font-render-setting move-toolbar gtk x-toolkit x multi-tty emacs)