Updated mediawiki/extensions
Project: mediawiki/extensions/Flow  e9083097946e08c2b464e11f52955542b33e10e2

Remove unused PersistenceException class

This was renamed to Flow\Exception\DataPersistenceException some
time ago, but it seems the class is still hanging around.

Change-Id: I9064aa01291d2c4c4bf92edf8e30b15989bdd40a