[darcs-users] Error loading darcs-beta in GHCi: duplicate symbol

[Robin Green]

I have just unsuccessfully tried to load a package which links against
darcs-beta in GHCi. It's a gitit plugin package, and gitit uses the GHC
API, driving GHCi programatically, to load plugins at runtime.
(I first tried linking against darcs 2.2.0, but there is a known issue
with that, so that didn't work.)

I get this error when I try to start gitit and it tries to load the
first plugin:

GHCi runtime linker: fatal error: I found a duplicate definition for
symbol sha224_h0
whilst processing object file
   /home/greenrd/.cabal/lib/darcs-beta-2.2.98.1/ghc-6.10.3/HSdarcs-beta-2.2.98.1.o
This could be caused by:
   * Loading two different object files which export the same symbol
   * Specifying the same object file twice on the GHCi command line
   * An incorrect `package.conf' entry, causing some object to be
     loaded twice.
GHCi cannot safely continue in this situation.  Exiting now.  Sorry.


How can I figure out what's causing this? Is there some library or
module that's been copied into a separate library on hackage, but still
exists in darcs-beta-2.2.98.1? Or might I be trying to load two versions
of the darcs package? How would I find out?

Thanks,
-- 
Robin