Add preparers for python

Bug: 181070625
Test: m nothing
Change-Id: I590ad62db6fd62719c83286780563cf6d55e3e17
diff --git a/python/binary.go b/python/binary.go
index 372b8a8..6061ad4 100644
--- a/python/binary.go
+++ b/python/binary.go
@@ -26,10 +26,14 @@
 )
 
 func init() {
-	android.RegisterModuleType("python_binary_host", PythonBinaryHostFactory)
+	registerPythonBinaryComponents(android.InitRegistrationContext)
 	android.RegisterBp2BuildMutator("python_binary_host", PythonBinaryBp2Build)
 }
 
+func registerPythonBinaryComponents(ctx android.RegistrationContext) {
+	ctx.RegisterModuleType("python_binary_host", PythonBinaryHostFactory)
+}
+
 type bazelPythonBinaryAttributes struct {
 	Main           string
 	Srcs           bazel.LabelList