Hack around failing jenkins tests

For some set of patches jenkins is running the command:

        php /srv/ssd/jenkins-slave/workspace/mwext-Flow-testextensions-master/maintenance/update.php --quiet --quick --schema /srv/ssd/jenkins-slave/workspace/mwext-Flow-testextensions-master/log/update_sql.log

that --schema argument means 'write all the sql to a file'.  update.php 
will still run the post-db maint scripts though, and those scripts in 
flow will only finish if the sql has actually been applied to the database.

My intuition is that the code in update.php is wrong and should not be running
post database update maintenance if all it did was write the sql out to a file
and not actually apply the updates. but if so, why is it only us with a problem?

As a temporary solution until we determine if core needs fixes use a reflection
property to see if DatabaseUpdater is currently outputting to a file handle.


Change-Id: I0e0909dd94c5bc6e796a0c64954243ec5ce9e1ab