Scheduled downtime on Dec 14

[Rainer Müller]

Hello,

due to maintenance on the network in the data center where our server is
hosted, there will be a 20-minute disconnection in the time frame given
below.

Start:  2018-12-14 03:00:00 UTC
End:    2018-12-14 05:00:00 UTC (expected)

This will mostly affect the website, Trac, and the mailing lists. GitHub
can be used as usual, but any WebHook sent from GitHub to Trac during
the downtime will fail and will have to be re-triggered manually once
the system is online again.

Rainer