only write when the displayname differs, but then announce it
refs #5212 and fixes#9112
Signed-off-by: Arthur Schiwon <blizzz@arthur-schiwon.de>
do not run into UniqueConstraintViolationException
… when an unmapped user logs in for the first time when background job
mode is ajax and no memcache was configured.
Signed-off-by: Arthur Schiwon <blizzz@arthur-schiwon.de>