[Engineering] Reverted to 1.28.0-wmf.8 once more.

Fri Jan 27 16:24:18 UTC 2017

The deployment of MediaWiki 1.29.0-wmf.9 is currently blocked and all wikis
have been reverted to wmf.8.  This latest revert is due to excessive
warnings which appeared in logs immediately after deploying to group2. The
warnings all read as follows:

Warning: Empty regular expression in
/srv/mediawiki/php-1.29.0-wmf.9/includes/parser/DateFormatter.php on line
200

This issue is tracked in https://phabricator.wikimedia.org/T156364 and
currently blocks further deployments.

More background:

A similar flood of log spam occurred after deploying the branch to group1,
however, the problem subsided after a while and did not reappear until
Thursday's deployment.

There have been recent changes to DateFormatter.php, however, the changes
do not appear to be the direct culprit. In fact, after rolling back the
changes, a different message appears in the log, however, with less
frequency than the line 200 error.

Several engineers have looked at this issue but so far we have not isolated
the root cause. Additional eyes on this issue would be welcomed and further
discussion should be directed to Phabricator. In the interest of keeping
everyone in the loop, I will follow up in this thread if/when there is a
resolution.

Regards,
Mukunda

---
Mukunda Modell
Wikimedia Release Engineering
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