Helps to verify that a command completed successfully.
Signed-off-by: NJohn Snow <jsnow@redhat.com>
Reviewed-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-id: 1423158090-25580-14-git-send-email-jsnow@redhat.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>