> And if there's a problem with the CI server, all you need to do is
> disable the webhook in one place in GitHub. Then the process can go on
> manually just like it has until now.

Actually I don't think the webhook can block anyone from doing anything
in GitHub even if the server is malfunctioning. The CI server's webhook
handler gave lots of HTTP 500 "Internal Server Error" responses to
GitHub during development and that didn't block any commits. So the CI
server is strictly a listener for human activity -- it doesn't force
anything.

The pull request status checks would be implemented so that the CI
server does a HTTP PUSH to GitHub's API to associate a build status with
a particular Git commit hash. But I don't think the build status has any
clout to block people from making commits or merging pull requests
unless we enable branch protection in that repo's GitHub settings.

In any case, if all else fails, we can disable the webhook in one place.