When a command is run via su from root, the exit status is always 0, even if
the command fails.

For example :

# service sssd status
sssd (pid  3009) is running...

# su - local_user -c "ls -8" ; echo $?
ls: invalid option -- '8'
Try `ls --help' for more information.
0

# service sssd stop
Stopping sssd:                                             [  OK  ]
# su - local_user -c "ls -8" ; echo $?
ls: invalid option -- '8'
Try `ls --help' for more information.
2

* User local_user is a local user (from /etc/passwd file)
* If we stop the sssd service(or remove pam_sss from pam 'session' section,
then the command exit status is correct.

How reproducible:
Always
Version-Release number of selected component (if applicable):
sssd-1.8.0-32.el6.x86_64


Steps to Reproduce:
1. Run, # su - local_user -c "ls -8" ; echo $?
2. check the return value.


Actual results: su always returns 0

Expected results: su returns failure if the command fails.