[SSSD] [sssd PR#544][opened] IPA: Qualify the externalUser sudo attribute

[jhrozek]

   URL: https://github.com/SSSD/sssd/pull/544
Author: jhrozek
 Title: #544: IPA: Qualify the externalUser sudo attribute
Action: opened

PR body:
"""
We broke the externalUser support with the introduction of the fully
qualified attributes, because the provider was saving the data verbatim,
but the sudo responder expects a fully qualified name.

Reproducer:
   on the server:
       ipa sudocmd-add --desc='For reading log files' /usr/bin/less
       ipa sudorule-add readfiles
       ipa sudorule-add-user --users=lcluser
       ipa sudorule-mod --hostcat=all readfiles

    then on the client:
       configure sssd with:
           id_provider = files
           sudo_provider = ipa
           ipa_domain = ipa.test

        run:
           sudo useradd lcluser
           sudo passwd lcluser
           su - lcluser
           sudo -l
"""

To pull the PR as Git branch:
git remote add ghsssd https://github.com/SSSD/sssd
git fetch ghsssd pull/544/head:pr544
git checkout pr544