Update opam2nix-package fix unbound variables

nix/default.nix

@@ -45,16 +45,16 @@ rec {
         setupHook = pkgs.writeText "setupHook.sh" ''
           addFramaCPath () {
             if test -d "''$1/lib/frama-c/plugins"; then
-              export FRAMAC_PLUGIN="''${FRAMAC_PLUGIN}''${FRAMAC_PLUGIN:+:}''$1/lib/frama-c/plugins"
-              export OCAMLPATH="''${OCAMLPATH}''${OCAMLPATH:+:}''$1/lib/frama-c/plugins"
+              export FRAMAC_PLUGIN="''${FRAMAC_PLUGIN:-}''${FRAMAC_PLUGIN:+:}''$1/lib/frama-c/plugins"
+              export OCAMLPATH="''${OCAMLPATH:-}''${OCAMLPATH:+:}''$1/lib/frama-c/plugins"
             fi
 
             if test -d "''$1/lib/frama-c"; then
-              export OCAMLPATH="''${OCAMLPATH}''${OCAMLPATH:+:}''$1/lib/frama-c"
+              export OCAMLPATH="''${OCAMLPATH:-}''${OCAMLPATH:+:}''$1/lib/frama-c"
             fi
 
             if test -d "''$1/share/frama-c/"; then
-              export FRAMAC_EXTRA_SHARE="''${FRAMAC_EXTRA_SHARE}''${FRAMAC_EXTRA_SHARE:+:}''$1/share/frama-c"
+              export FRAMAC_EXTRA_SHARE="''${FRAMAC_EXTRA_SHARE:-}''${FRAMAC_EXTRA_SHARE:+:}''$1/share/frama-c"
             fi
 
           }

nix/frama-ci.nix

@@ -5,7 +5,7 @@ let
     src = builtins.fetchGit {
             "url" = "https://bobot:${password}@git.frama-c.com/frama-c/Frama-CI.git";
             "name" = "Frama-CI";
-            "rev" = "85ba4a2c716d3f992f75bd838463a36b86cf7ccb";
+            "rev" = "4add9658dfda894a5db9de59aa7a5657c8cf7b2b";
             "ref" = "feature/ci/update-opam";
     };
  in