What concerns the original issue, I found the error in my filters. Due to interaction of new list name and old filters, all the mails were automatically archived and tagged with Pywikibot-bugs. Did I already told that I hate to spend my time with updating the working environment all the time instead of working?
Thanks to Amir, the discussion turned interesting. I just listen, as I was stuck somewhere at Bugzilla and SVN and compat, and couldn't return as developer since that (although I have ideas what to do).