roundup-admin@tryton.org: Failed issue tracker submission]
[...]
The message you sent to roundup did not contain a properly formed subject
line. The subject must contain a class name or designator to indicate the
'topic' of the message. For example:
    Subject: [issue] This is a new issue
      - this will create a new issue in the tracker with the title 'This is
        a new issue'.
    Subject: [issue1234] This is a followup to issue 1234
      - this will append the message's contents to the existing issue 1234
        in the tracker.

Subject was: '[PATCH] [3341]'
[...]