Hi,
Running MediaWiki 1.30.0 on Centos7 + PHP7.0 (from rpms.remirepo.net).
Due to another application requirement I have this in my php.ini:
date.timezone = Europe/Paris
which is GMT+1 (outside daylight saving time).
When MediaWiki stores a session object in the objectcache, I get an exptime such as this for a login at 10:40 GMT+1:
MariaDB [wiki]> SELECT keyname, exptime FROM objectcache WHERE keyname LIKE "%Sess%";
+-------------------------------------------------+---------------------+
| keyname | exptime |
+-------------------------------------------------+---------------------+
| wiki:MWSession:j21l5ngv5u0u0nnc4vh0gr23bbtnr07e | 2018-01-10 10:40:10 |
+-------------------------------------------------+---------------------+
which is the session expiration now+1h, as GMT, so 11:40 localtime.
However when the session is read, the timestamp is interpreted as the current timezone (GMT+1).
(now+1h)-1h = now, so the session is expired immediately and I get disconnected.
When unsetting date.timezone and restarting Apache, this problem does not happen.
So it seems to be some asymmetry between setting/getting a DB cache timestamp when date.timezone is set.