Disable paygen update tests on daisy_spring.

Paygen update tests with source payloads older than R38 can cause
daisy_spring devices to fail, after which they are hard to recover.
This change applies a point hack that blocks the tests from running
in all cases on daisy_spring.

This hack will need to stay in place until a workaround is found
that prevents the device failures, or we find a reliable recovery
procedure for the failed devices.

BUG=chromium:429325
TEST=cbuildbot/cbuildbot_run_unittest.py

Change-Id: I467d41fdaa64cfc614e6e0cea963485e8fed4ce2
Reviewed-on: https://chromium-review.googlesource.com/226872
Reviewed-by: David James <davidjames@chromium.org>
Tested-by: Richard Barnette <jrbarnette@chromium.org>
diff --git a/lib/paygen/paygen_build_lib.py b/lib/paygen/paygen_build_lib.py
index 4777c3c..481cead 100644
--- a/lib/paygen/paygen_build_lib.py
+++ b/lib/paygen/paygen_build_lib.py
@@ -880,6 +880,18 @@
     Args:
       suite_name: The name of the test suite.
     """
+    # Because of crbug.com/383481, if we run delta updates against
+    # a source payload earlier than R38, the DUTs assigned to the
+    # test may fail when rebooting.  The failed devices can be hard
+    # to recover.  The bug affects spring and skate, but as of this
+    # writing, only spring is still losing devices.
+    #
+    # So, until it's all sorted, we're going to skip testing on
+    # spring devices.
+    if self._archive_board == 'daisy_spring':
+      logging.info('Skipping payload autotest for board %s',
+                   self._archive_board)
+      return
     timeout_mins = cbuildbot_config.HWTestConfig.DEFAULT_HW_TEST_TIMEOUT / 60
     if self._run_on_builder:
       try: