hedgewars: use haskellPackages.network_2_6_3_1

gameServer/hedgewars-server.cabal indicates network version needs
to be < 3.0.

pkgs/games/hedgewars/default.nix

@@ -6,8 +6,9 @@
 }:
 
 let
+  # gameServer/hedgewars-server.cabal depends on network < 3
   ghc = ghcWithPackages (pkgs: with pkgs; [
-          SHA bytestring entropy hslogger network pkgs.zlib random
+          SHA bytestring entropy hslogger network_2_6_3_1 pkgs.zlib random
           regex-tdfa sandi utf8-string vector
         ]);
 
@@ -40,6 +41,15 @@ mkDerivation rec {
     "-DNOSERVER=${if withServer then "OFF" else "ON"}"
   ];
 
+
+  # hslogger brings network-3 and network-bsd which conflict with 
+  # network-2.6.3.1
+  preConfigure = ''
+    substituteInPlace gameServer/CMakeLists.txt \
+      --replace "haskell_flags}" \
+        "haskell_flags} -package network-2.6.3.1 -hide-package network-bsd"
+  '';
+
   NIX_LDFLAGS = lib.concatMapStringsSep " " (e: "-rpath ${e}/lib") [
     SDL2.out
     SDL2_image