Description of problem:
IPA key authentication logs false error message for root user.

Systems configured with IPA server for authentication and authentication to
root user is via public key stored in local authorized key and not in IPA.

Now whenever login to system with root user it logs below error messages but
same is not the case when we login with IPA user.

 error: AuthorizedKeysCommand /usr/bin/sss_ssh_authorizedkeys returned status 1

I guess authentication to root is also trying to retrieve the key from IPA
server which is resulting into the error. see the error below.

[root@system log]# sss_ssh_authorizedkeys root
Error looking up public keys
[root@system log]#

Version-Release number of selected component (if applicable):
RHEL 7.2

How reproducible:
100%


Additional info:
In the SSH responder, we ignore root as we should:
 69     if (strcmp(cmd_ctx->name, "root") == 0) {
 70         ret = ENOENT;
 71         goto done;
 72     }

But in the SSH client tool, we fail if the function above returns ENOENT:
 86     /* look up public keys */
 87     ret = sss_ssh_get_ent(mem_ctx, SSS_SSH_GET_USER_PUBKEYS,
 88                           pc_user, pc_domain, NULL, &ent);
 89     if (ret != EOK) {
 90         DEBUG(SSSDBG_CRIT_FAILURE,
 91               "sss_ssh_get_ent() failed (%d): %s\n", ret, strerror(ret));
 92         ERROR("Error looking up public keys\n");
 93         ret = EXIT_FAILURE;
 94         goto fini;
 95     }