use the sourceforge mirrors everywhere

find pkgs -name "*.nix" -exec sed -r \
    "s|https?://downloads.sourceforge.net/|mirror://sourceforge/|g" -i {} \;

pkgs/games/instead/default.nix

@@ -32,7 +32,7 @@ stdenv.mkDerivation rec {
   name = "instead-" + version;
 
   src = fetchurl {
-    url = "http://downloads.sourceforge.net/project/instead/instead/${version}/instead_${version}.tar.gz";
+    url = "mirror://sourceforge/project/instead/instead/${version}/instead_${version}.tar.gz";
     sha256 = "1ldisjkmmcpnmv4vsd25dc1sfiwbr9fcn3hxhl78i4jwlyqgrms8";
   };
 

pkgs/games/odamex/default.nix

@@ -3,7 +3,7 @@
 stdenv.mkDerivation rec {
   name = "odamex-0.7.0";
   src = fetchurl {
-    url = http://downloads.sourceforge.net/odamex/odamex-src-0.7.0.tar.bz2;
+    url = mirror://sourceforge/odamex/odamex-src-0.7.0.tar.bz2;
     sha256 = "0cb6p58yv55kdyfj7s9n9xcwpvxrj8nyc6brw9jvwlc5n4y3cd5a";
   };
 

pkgs/games/vassal/default.nix

@@ -4,7 +4,7 @@ stdenv.mkDerivation rec {
   name = "VASSAL-3.2.15";
 
   src = fetchurl {
-    url = "http://downloads.sourceforge.net/vassalengine/${name}-linux.tar.bz2";
+    url = "mirror://sourceforge/vassalengine/${name}-linux.tar.bz2";
     sha256 = "10ng571nxr5zc2nlviyrk5bci8my67kq3qvhfn9bifzkxmjlqmk9";
   };