Alright, it looks like it would be a good idea to track down which patch(es)
is/are trying to modify
  ./compiler/rename/RnPat.lhs
and
  ./compiler/rename/RnExpr.lhs-boot
and breaking (and of course, it may not be the patch itself that is at fault,
but a prior one)

Also, if we get it to a state where without trying to pull that patch darcs2
works fine, but darcs1 still has the gzopen error, then we can assume we've got
a separate issue to deal with.