haskell-darcs: re-generate expression with recent version of cabal2nix

pkgs/applications/version-management/darcs/default.nix

@@ -15,11 +15,11 @@ cabal.mkDerivation (self: {
     utf8String vector zlib
   ];
   extraLibraries = [ curl ];
+  doCheck = false;
   postInstall = ''
     mkdir -p $out/etc/bash_completion.d
     mv contrib/darcs_completion $out/etc/bash_completion.d/darcs
   '';
-  doCheck = false;
   meta = {
     homepage = "http://darcs.net/";
     description = "a distributed, interactive, smart revision control system";