bug#21972: 24.5; Running 'bash -i -c' via shell-command hangs on FreeBSD

[Davor Cubranic <davor.cubranic@alumni.cs.ubc.ca>]

On FreeBSD, running:

  M-x shell-command
  /usr/local/bin/bash -i -c "echo hello"

hangs until you press C-g (twice). I can see the bash process running at
100% via `top` until C-g kills it.

Adding `--norc --noprofile` to the command still hangs, so it's not
anything about the shell initialization files. The `-i` option is the
key: without it, everything works fine.

Running the same command via `async-shell-command` does not hang: Bash
outputs "hello" in the "*Async Shell Command*" buffer and exits.

Both Emacs and Bash are standard FreeBSD 10 binary packages installed
via `pkg`. (emacs24-24.5_1,3 and bash-4.3.42, respectively).


In GNU Emacs 24.5.1 (amd64-portbld-freebsd10.1, GTK+ Version 2.24.28)
 of 2015-11-13 on builds.pcbsd.org
Windowing system distributor `The X.Org Foundation', version 11.0.11704000
Configured using:
 `configure --localstatedir=/var --disable-acl --with-dbus
 --without-file-notification --with-gconf --with-gif --with-gnutls
 --with-gsettings --with-jpeg --with-m17n-flt --with-imagemagick
 --with-libotf --with-png --with-toolkit-scroll-bars --with-rsvg
 --with-tiff --with-x --with-xft --with-xim --with-xml2 --with-xpm
 --with-x-toolkit=gtk2 --with-sound=oss --x-libraries=/usr/local/lib
 --x-includes=/usr/local/include --prefix=/usr/local
 --mandir=/usr/local/man --infodir=/usr/local/share/emacs/info/
 --build=amd64-portbld-freebsd10.1 'CFLAGS=-O2 -pipe -fstack-protector
 -fno-strict-aliasing' CPPFLAGS=-I/usr/local/include 'LDFLAGS=
 -L/usr/local/lib -Wl,-rpath=/usr/lib:/usr/local/lib -fstack-protector''

Important settings:
  value of $LC_ALL: en_US.UTF-8
  value of $LANG: en_US.UTF-8
  locale-coding-system: utf-8-unix

Major mode: Lisp Interaction

Minor modes in effect:
  tooltip-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.

Load-path shadows:
None found.

Features:
(shadow sort gnus-util mail-extr emacsbug message format-spec rfc822 mml
easymenu mml-sec mm-decode mm-bodies mm-encode mail-parse rfc2231
mailabbrev gmm-utils mailheader sendmail rfc2047 rfc2045 ietf-drums
mm-util help-fns mail-prsvr mail-utils time-date tooltip electric
uniquify 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
prog-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 nadvice 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)

Memory information:
((conses 16 71124 7466)
 (symbols 48 17557 0)
 (miscs 40 33 88)
 (strings 32 9070 4601)
 (string-bytes 1 248833)
 (vectors 16 8904)
 (vector-slots 8 382922 19034)
 (floats 8 63 88)
 (intervals 56 201 7)
 (buffers 960 11))