PR status only take the first check into account

I was confused today because my PR was marked as "build: success" on Trac, but it had fail on github.

Investigating the issue, I discovered that the javascript that figures out the status of a PR only takes the first check into account: https://github.com/django/code.djangoproject.com/blob/a8774abd91108baa70eb936c5ad5a736dd646b5b/trac-env/htdocs/tickethacks.js#L124

Considering we have around 50 checks, I don't think this logic is accurate.

I would suggest that the status should be "building" if any individual check has status=building, "error" if at least one check has status=error, and "success" only if all checks have status=success (not sure if there are other statues to take into account)