failed grep should cause subshell to exit

[David Lehmann]

### should never see done****

** **

% uname -a

Linux xxxxx 2.6.32-279.2.1.el6.x86_64 #1 SMP Thu Jul 5 21:08:58 EDT 2012
x86_64 x86_64 x86_64 GNU/Linux

% bash --version

GNU bash, version 4.1.2(1)-release (x86_64-redhat-linux-gnu)



(****

set -ex****

** **

echo hello >x****

grep hello x****

! grep hello x****

echo $?****


### should not see "done" because set -e

echo done****

)