Browser tests are failing on beta labs.
I checked some failing edit existing title and edit existing post, e.g. https://saucelabs.com/jobs/f05b8c2b257946c1b359f5b789ec0b8d , and the screencast ends with an errorbox containing

The error message received was: Database query error

deployment-bastion:/data/project/log/dberror.log contains 16 very similar entries complaining Duplicate entry for key 'flow_revision_unique_parent' in flow_revision, e.g.

Tue Jan 21 20:40:47 UTC 2014 deployment-apache32 enwiki Flow\Data\RevisionStorage::insert 10.4.0.53 1062 Duplicate entry '�\x04��\�\x04�\x02\x16>� for key 'flow_revision_unique_parent' (10.4.0.53) INSERT INTO flow_revision (rev_id,rev_user_id,rev_user_ip,rev_parent_id,rev_change_type,rev_type,rev_content,rev_flags,rev_mod_state,rev_mod_user_id,rev_mod_user_ip,rev_mod_timestamp,rev_mod_reason,rev_last_edit_id,rev_edit_user_id,rev_edit_user_ip) VALUES ('�\"�u4�@\x1d\x02\x16>92','820',NULL,'�\x04��\\�\x04�\x02\x16>�,'edit-title','post','

The browser tests all hit the same Talk:Flow-QA page and can run concurrently, so it's possible two tests are trying to edit the same topic and post. Maybe upcoming edit conflict handling will report a conflict in place of the DB error.

• This bug has been marked as a duplicate of bug 60349 ***