pushimage: Copy stateful.tgz to chromeos-releases.

Copy over the stateful.tgz file to chromeos-releases, so we can run
payload testing without referring to chromeos-image-archive.

BUG=chromium:523122
TEST=Unittests

Change-Id: I9b5a119c4217cbe670da41f6cf2896f2fa61b38c
Reviewed-on: https://chromium-review.googlesource.com/295219
Commit-Ready: Don Garrett <dgarrett@chromium.org>
Tested-by: Don Garrett <dgarrett@chromium.org>
Reviewed-by: Don Garrett <dgarrett@chromium.org>
diff --git a/scripts/pushimage_unittest.py b/scripts/pushimage_unittest.py
index 76618e4..1dd7c4a 100644
--- a/scripts/pushimage_unittest.py
+++ b/scripts/pushimage_unittest.py
@@ -197,7 +197,7 @@
 
     urls = pushimage.PushImage('/src', 'test.board', 'R34-5126.0.0',
                                sign_types=['recovery'])
-    self.assertEqual(self.gs_mock.call_count, 18)
+    self.assertEqual(self.gs_mock.call_count, 20)
     self.assertTrue(self.mark_mock.called)
     self.assertEqual(urls, EXPECTED)
 
@@ -205,7 +205,7 @@
     """Verify nothing is signed when we request an unavailable type"""
     urls = pushimage.PushImage('/src', 'test.board', 'R34-5126.0.0',
                                sign_types=['nononononono'])
-    self.assertEqual(self.gs_mock.call_count, 16)
+    self.assertEqual(self.gs_mock.call_count, 18)
     self.assertFalse(self.mark_mock.called)
     self.assertEqual(urls, {})