Serialize PythonUtils#GET_INIT_PY_FILES as a singleton so that object equality
holds in the check in Runfiles.Builder#merge.

PiperOrigin-RevId: 191341008
diff --git a/src/main/java/com/google/devtools/build/lib/rules/python/PythonUtils.java b/src/main/java/com/google/devtools/build/lib/rules/python/PythonUtils.java
index 39d88ab..7acd86c 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/python/PythonUtils.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/python/PythonUtils.java
@@ -39,7 +39,6 @@
 
   private static final FileType REQUIRES_INIT_PY = FileType.of(".py", ".so", ".pyc");
 
-  @AutoCodec
   static class GetInitPyFiles implements Runfiles.EmptyFilesSupplier {
     @Override
     public Iterable<PathFragment> getExtraPaths(Set<PathFragment> manifestPaths) {
@@ -47,6 +46,7 @@
     }
   }
 
+  @AutoCodec
   public static final Runfiles.EmptyFilesSupplier GET_INIT_PY_FILES = new GetInitPyFiles();
 
   private PythonUtils() {