release.nix: prepend to existing $PATH

release.nix

@@ -62,7 +62,7 @@ let
   ihaskellSh = cmd: extraArgs: nixpkgs.writeScriptBin "ihaskell-${cmd}" ''
     #! ${nixpkgs.stdenv.shell}
     export GHC_PACKAGE_PATH="$(echo ${ihaskellEnv}/lib/*/package.conf.d| tr ' ' ':'):$GHC_PACKAGE_PATH"
-    export PATH="${nixpkgs.stdenv.lib.makeBinPath ([ ihaskellEnv jupyter ] ++ systemPackages nixpkgs)}"
+    export PATH="${nixpkgs.stdenv.lib.makeBinPath ([ ihaskellEnv jupyter ] ++ systemPackages nixpkgs)}:$PATH"
     ${ihaskellEnv}/bin/ihaskell install -l $(${ihaskellEnv}/bin/ghc --print-libdir) --use-rtsopts="${rtsopts}" && ${jupyter}/bin/jupyter ${cmd} ${extraArgs} "$@"
   '';
 in