Issue https://bugs.python.org/issue31530 use a title "[2.7] Python 2.7 readahead feature of file objects is not thread safe" for the ticket. When trying to reply to ticket items via email, roundup sent back an error message stating:
There were problems handling your subject line argument list:
- not of form [arg=value,value,...;arg=value,value,...]
Subject was: "Re: [issue31530] [2.7] Python 2.7 readahead feature of
file objects is not thread safe"
Apparently, it was picking up the "[2.7]" as an argument indicator. Removing the "[2.7]" from the title made the problem go away.
Since I don't think anyone (apart from maybe Roundup itself) is using [...] for passing arguments to it, it would probably be better to disable such parsing logic for email messages altogether or at least filter/quote and such occurrences in ticket titles so that they are not parsed.