The new rccontinue parameter is not properly handled:
- rc_id is not included in the ORDER BY
- continue handling checks the wrong value for $params['dir'], and so fails with the default dir=older
- continue handling assumes for dir=older that the query will be "ORDER BY rc_timestamp DESC, rc_id ASC", which would filesort.
Gerrit change to follow momentarily, once I have the bug number for the commit summary.