Fix assign instead of compare
    
    Commit 53e0b2255d92c9c21c19306cf37cc8de0476dc9c introduced a minor bug.
    Instead of comparing errno to ENOENT, the check assigned ENOENT to
    errno.
    
    Coverity: CID 337082
    See: https://pagure.io/freeipa/issue/4607
    Signed-off-by: Christian Heimes <cheimes@redhat.com>
    Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>