Remove boards restrictions for cbuildbot --hwtest

Instead of fail the build, post a warning that hwtest step may fail if the
specified board is not a released platform or it is a generic overlay.

BUG=chromium:264871
TEST=tested with cbuildbot --remote, pass unittest in chroot:
     ./cbuildbot_config_unittest.py

Change-Id: Ibbf597a23d2f171c81e864377dc38cc24e449d3c
Reviewed-on: https://gerrit.chromium.org/gerrit/63805
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Tested-by: Dan Shi <dshi@chromium.org>
Commit-Queue: Dan Shi <dshi@chromium.org>
diff --git a/scripts/cbuildbot.py b/scripts/cbuildbot.py
index 0e3d04f..df340fd 100644
--- a/scripts/cbuildbot.py
+++ b/scripts/cbuildbot.py
@@ -1293,18 +1293,15 @@
     cros_build_lib.logger.setLevel(logging.WARNING)
 
     # Verify configs are valid.
-    # If hwtest flag is enabled, verify that config board is in whitelist.
+    # If hwtest flag is enabled, post a warning that HWTest step may fail if the
+    # specified board is not a released platform or it is a generic overlay.
     for bot in args:
       build_config = _GetConfig(bot)
       if options.hwtest:
-        if not set(build_config['boards']).issubset(
-               set(constants.HWTEST_BOARD_WHITELIST)):
-          cros_build_lib.Die('The test lab is unable to run hwtest tryjobs '
-                             'with the given board(s). The currently '
-                             'supported boards are %s. If you are root '
-                             'causing a critical bug and need temporary '
-                             'support please contact the lab '
-                             'team.' % constants.HWTEST_BOARD_WHITELIST)
+        cros_build_lib.Warning(
+            'If %s is not a released platform or it is a generic overlay, '
+            'the HWTest step will most likely not run; please ask the lab '
+            'team for help if this is unexpected.' % build_config['boards'])
 
     # Verify gerrit patches are valid.
     print 'Verifying patches...'