new routing issues

Around 18:36 UTC today Nagios started noticing network reachability issues with mini-nag:

[mini-nag/auto-dns] web-chi-03.torproject.org is considered BAD (ping-check (50.00%)) @ 18:36:32 +0000
[mini-nag/auto-dns] moly.torproject.org is considered BAD (ping-check (50.00%)) @ 18:36:32 +0000
[mini-nag/auto-dns] web-cymru-01.torproject.org is considered BAD (depends; ping-check (50.00%)) @ 18:36:32 +0000

Furthermore, via IRC some users reported GitLab being down, and several chives users dropped out of IRC.

The incident seems to have lasted only a few minutes, and systems all appear to be in working order again, but we're opening an incident ticket to follow-up. This might be related to #40432 (closed)