script, broken test options/return

[Ruediger Meier <sweet_f_a@gmx.de>]

Hi,

on my system (interactive bash on openSUSE 13.1) the "return" subtest 
of "script/options" is broken since 54c6611d.

Seems that input from /dev/null makes the difference. Reproduce like
this:

$ export SCRIPT_DEBUG=all 
$ ./script --command "exit 1" out_good >/dev/null            2>dbg_good
$ ./script --command "exit 1" out_bad  >/dev/null </dev/null 2>dbg_bad
^C <abort ctrl-C>

$ head -n 20 dbg_good dbg_bad
==> dbg_good <==
25703: script:       IO: master fd: 3
25703: script:   SIGNAL: signal fd=5
25703: script:     POLL: calling poll()
25703: script:     POLL: poll() rc=1
25703: script:     POLL:  active pfd[signal].fd=5 POLLIN
25703: script:   SIGNAL: signal FD 5 active
25703: script:     MISC: waiting for child
25703: script:     POLL: calling poll()
25703: script:     POLL: poll() rc=0
25703: script:     POLL: setting die=1
25703: script:     POLL: poll() done
25703: script:     MISC: done!

==> dbg_bad <==
25708: script:       IO: master fd: 3
25708: script:   SIGNAL: signal fd=5
25708: script:     POLL: calling poll()
25708: script:     POLL: poll() rc=1
25708: script:     POLL:  active pfd[stdin].fd=0 POLLIN
25708: script:       IO: 0 FD active
25708: script:     POLL: calling poll()
25708: script:     POLL: poll() rc=1
25708: script:     POLL:  active pfd[stdin].fd=0 POLLIN
25708: script:       IO: 0 FD active
25708: script:     POLL: calling poll()
25708: script:     POLL: poll() rc=1
25708: script:     POLL:  active pfd[stdin].fd=0 POLLIN
25708: script:       IO: 0 FD active
25708: script:     POLL: calling poll()
25708: script:     POLL: poll() rc=1
25708: script:     POLL:  active pfd[stdin].fd=0 POLLIN
25708: script:       IO: 0 FD active
25708: script:     POLL: calling poll()
25708: script:     POLL: poll() rc=1
...

cu,
Rudi