Fix a subtle proguard incremental build error

build/android/gyp/proguard.py

Index: build/android/gyp/proguard.py
diff --git a/build/android/gyp/proguard.py b/build/android/gyp/proguard.py
index 071f32438439df45f57c169c8d6dec3993cf7d3f..8cfa27b7da61b71e3a70151fdb62972600ee1b9c 100755
--- a/build/android/gyp/proguard.py
+++ b/build/android/gyp/proguard.py
@@ -66,6 +66,18 @@ def main(args):
   args = build_utils.ExpandFileArgs(args)
   options = _ParseOptions(args)
 
+  # Work around cases where we switch from a non-proguard setup
+  # to proguard. The output jar might exist and might be a hardlink
+  # to the input jar, so remove the output before doing anything
+  # in that case to avoid an incremental build failure.
+  try:
+    out_inode = os.stat(options.output_path).st_ino
+  except OSError:
+    out_inode = None
+  if (out_inode and
+      out_inode in (os.stat(injar).st_ino for injar in options.input_paths)):
+    os.unlink(options.output_path)
+
   proguard = proguard_util.ProguardCmdBuilder(options.proguard_path)
   proguard.injars(options.input_paths)
   proguard.configs(options.proguard_configs)