When the Chrome OS Pre-CQ picks up a CL, the URLs that it adds to the ticket to follow what is going on are invalid. For example, see the commit bot on:
https://chromium-review.googlesource.com/#/c/416235/

The Pre-Commit Queue has picked up your change. You can follow along at 
(binhost-pre-cq) : https://luci-milo.appspot.com/buildbot/https://uberchromegw.corp.google.com/i/chromiumos.tryserver/pre_cq/9680
(mixed-c-pre-cq) : https://luci-milo.appspot.com/buildbot/https://uberchromegw.corp.google.com/i/chromiumos.tryserver/compile_only_pre_cq/13398
(mixed-a-pre-cq) : https://luci-milo.appspot.com/buildbot/https://uberchromegw.corp.google.com/i/chromiumos.tryserver/compile_only_pre_cq/13399
(mixed-b-pre-cq) : https://luci-milo.appspot.com/buildbot/https://uberchromegw.corp.google.com/i/chromiumos.tryserver/compile_only_pre_cq/13396
(rambi-pre-cq) : https://luci-milo.appspot.com/buildbot/https://uberchromegw.corp.google.com/i/chromiumos.tryserver/pre_cq/9681 .

Clicking on any of the links gives a 404