bazel_4: add default tools to buildInputs (to be accessible from repository rules)

Previously the customBash wrapper added the default tools to the PATH of commands from repository rules (which are run in the same environment as Bazel).

pkgs/development/tools/build-managers/bazel/bazel_4/default.nix

@@ -75,7 +75,7 @@ let
     for i in ${builtins.toString srcDeps}; do cp $i $out/$(stripHash $i); done
   '';
 
-  defaultShellPath = lib.makeBinPath
+  defaultShellUtils =
     # Keep this list conservative. For more exotic tools, prefer to use
     # @rules_nixpkgs to pull in tools from the nix repository. Example:
     #
@@ -120,6 +120,8 @@ let
       zip
     ];
 
+  defaultShellPath = lib.makeBinPath defaultShellUtils;
+
   # Java toolchain used for the build and tests
   javaToolchain = "@bazel_tools//tools/jdk:toolchain_${buildJdkName}";
 
@@ -527,10 +529,7 @@ stdenv.mkDerivation rec {
     in lib.optionalString stdenv.hostPlatform.isDarwin darwinPatches
      + genericPatches;
 
-  buildInputs = [
-    buildJdk
-    python3
-  ];
+  buildInputs = [buildJdk] ++ defaultShellUtils;
 
   # when a command can’t be found in a bazel build, you might also
   # need to add it to `defaultShellPath`.