Updated mediawiki/extensions
Project: mediawiki/extensions/CentralAuth  7a38d8ebcdb7cddbd9e0a1036dd3dcb48105d50b

gu_home_db can already be '' in the database.

Improve check to do '' or null, don't set to '' either

Change-Id: Icda2b8b76899935a798a017a4aeb7fa9ed8a09ba