Forster recently went awol and needed stabbing. When it came back up, the mailman process wasn't running. I tried manually starting it but was getting an error message very similar to https://pastebin.canonical.com/56096/ which is referenced by David in https://wiki.canonical.com/IncidentReports/2011-11-21-LP-More-Mailman-delays. After trying to start it a few times, each time removing /srv/lists.launchpad.net/var/mailman/data/master-qrunner.pid per the logs, it still was failing.
Then I noticed there was another pidfile - /srv/lists.launchpad.net/var/production-mailman-launchpad.pid. Once this was removed, the mailman process started fine. So, it seems the initscript is giving us misleading information and silently fails if the second pidfile is stale.
Didn'rt we see this happen several years ago when mailman shared an LPCONFIG with other production evironments? Has the configs changed recently so that mailman's config also thinks it is the config for other environments?