I have attached the exim and roundup logs from handling a reply to this issue.
You can see that roundup is receiving the mail twice, the first is processed
normally and the second fails "due to concurrent update". If I am reading the
exim log rightly this machine is subscribed to darcs devel as
darcs-bugs@darcs.net and as darcs-bugs@darcsvm.osuosl.org. I think we need a
list admin to remove the darcs-bugs@darcsvm.osuosl.org subscriber from the list(s).