Title: #271: pam: properly support UPN logon names
Many logon applications like /bin/login or sshd canonicalize the user
name before they call pam_start() and hence the UPN is not seen by
SSSD's pam responder. But some like e.g. gdm don't and authentication
might fail if a UPN is used.
The reason is that currently the already parsed short name of the user
was used in the cache_req and hence the cache_req was not able to fall
back to the UPN lookup code. This patch uses the name originally
provided by the user as input to allow the fallback to the UPN lookup.
To pull the PR as Git branch:
git remote add ghsssd https://github.com/SSSD/sssd
git fetch ghsssd pull/271/head:pr271
git checkout pr271