GN: forward_variables_from shouldn't clobber vars.

third_party/jmake/BUILD.gn

 # Copyright 2015 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/android/rules.gni")
 
 java_binary("jmake") {
   java_files = [
     "src/org/pantsbuild/jmake/CompatibilityChecker.java",
     "src/org/pantsbuild/jmake/BinaryFileWriter.java",
     "src/org/pantsbuild/jmake/PCDEntry.java",
     "src/org/pantsbuild/jmake/TextProjectDatabaseWriter.java",
     "src/org/pantsbuild/jmake/Base64.java",
     "src/org/pantsbuild/jmake/PCDContainer.java",
     "src/org/pantsbuild/jmake/Main.java",
     "src/org/pantsbuild/jmake/ClassFileReader.java",
     "src/org/pantsbuild/jmake/ClassPath.java",
     "src/org/pantsbuild/jmake/BinaryFileReader.java",
     "src/org/pantsbuild/jmake/PrivateException.java",
     "src/org/pantsbuild/jmake/ClassInfo.java",
     "src/org/pantsbuild/jmake/BinaryProjectDatabaseWriter.java",
     "src/org/pantsbuild/jmake/PCDManager.java",
     "src/org/pantsbuild/jmake/TextProjectDatabaseReader.java",
     "src/org/pantsbuild/jmake/RefClassFinder.java",
     "src/org/pantsbuild/jmake/Utils.java",
     "src/org/pantsbuild/jmake/PublicExceptions.java",
     "src/org/pantsbuild/jmake/BinaryProjectDatabaseReader.java",
   ]
   main_class = "org.pantsbuild.jmake.Main"
-  enable_incremental_javac = false
+  enable_incremental_javac_override = false
 }