Okay, I've verified that the emacs-bug repository is also corrupt.  There is a
reference in a conflictor to a patch

    hunk ./emacs 263
    -(load "~/.emacs.d/newsticker.el")
    +;;(load "~/.emacs.d/newsticker.el")

which doesn't exist in the history prior to that conflict.  You can view this using

darcs changes -v 2>&1 | less

There is a patch matching this description *after* these changes, so it's
possible that the corruption got introduced when that patch was commuted beyond
them, or there might have been another patch that was obliterated, or that
exists in a different repository that wasn't pulled.  In any case, while this
repository is proof that there's a bug in darcs, it doesn't allow us to
reproduce that bug, so someone is going to need to do more work to track it
down!  :(

I've got very intermittent connectivity right now and not all that much time, so
I'd appreciate some help on this one.

David