Scripts should not care about closed tree when committing.

PRESUBMIT.py

Index: PRESUBMIT.py
diff --git a/PRESUBMIT.py b/PRESUBMIT.py
index 819331f9e5b33d2ea65e33c49e979847767db07f..75e16e3bd79df3876e046983ee9c645cde0c9be0 100644
--- a/PRESUBMIT.py
+++ b/PRESUBMIT.py
@@ -58,6 +58,17 @@ def _CommonChecks(input_api, output_api):
   return results
 
 
+def _SkipTreeCheck(input_api, output_api):
+  """Check the env var whether we want to skip tree check.
+     Only skip if src/version.cc has been updated."""
+  src_version = 'src/version.cc'
+  FilterFile = lambda file: file.LocalPath() == src_version
+  if not input_api.AffectedSourceFiles(
+      lambda file: file.LocalPath() == src_version):
+    return False
+  return input_api.environ.get('PRESUBMIT_TREE_CHECK') == 'skip'
+
+
 def CheckChangeOnUpload(input_api, output_api):
   results = []
   results.extend(_CommonChecks(input_api, output_api))
@@ -69,7 +80,8 @@ def CheckChangeOnCommit(input_api, output_api):
   results.extend(_CommonChecks(input_api, output_api))
   results.extend(input_api.canned_checks.CheckChangeHasDescription(
       input_api, output_api))
-  results.extend(input_api.canned_checks.CheckTreeIsOpen(
-      input_api, output_api,
-      json_url='http://v8-status.appspot.com/current?format=json'))
+  if not _SkipTreeCheck(input_api, output_api):
+    results.extend(input_api.canned_checks.CheckTreeIsOpen(
+        input_api, output_api,
+        json_url='http://v8-status.appspot.com/current?format=json'))
   return results