nix: add latest version of batsim in nix file, for those who want to use it..

default.nix

@@ -39,6 +39,17 @@ let
       dontStrip = true;
     });
 
+    # Later version of batsim, with memleak bug fixed
+    batsim_latest = kapack.batsim.overrideAttrs (attr: rec{
+      name = "batsim";
+      version = "e3dbc246c5e3acd117a84909d351b94bfb6e4a59"; # commit "code: prevent temporary memleak for zmq msgs"
+      src = fetchgit rec {
+        url = "https://framagit.org/batsim/batsim.git";
+        rev = version;
+        sha256 = "sha256-+SGdNrPjRTGInrEQyFMCWcPIESD5yS+Enc1WRDCdKbQ=";
+      };
+    });
+
     # Batmen integration tests.
     test = pkgs.mkShell rec {
       shellHook = ''