Updated to arc-runtime-54.5021.667.0
diff --git a/src/build/lint_ignore.txt b/src/build/lint_ignore.txt
index 4968d4c..8038b8d 100644
--- a/src/build/lint_ignore.txt
+++ b/src/build/lint_ignore.txt
@@ -66,6 +66,10 @@
   # Having ARC MOD confuses this script.
   "src/build/arc.el": ["analyze_diffs"],
 
+  # This is from NaCl SDK Tools.
+  "canned/host/nacl_sdk/download.py": ["flake8"],
+  "canned/host/nacl_sdk/sdk_update.py": ["flake8"],
+
   # This is part of the Chrome apps platform downloaded from GitHub:
   # https://github.com/petele/IAPDemo/blob/master/scripts/buy.js
   "canned/cws/buy.js": ["gjslint"]
diff --git a/src/build/sync_nacl_sdk.py b/src/build/sync_nacl_sdk.py
index b647548..555567e 100755
--- a/src/build/sync_nacl_sdk.py
+++ b/src/build/sync_nacl_sdk.py
@@ -9,6 +9,7 @@
 import argparse
 import logging
 import os
+import shutil
 import sys
 import urllib
 
@@ -22,6 +23,9 @@
 _NACL_MIRROR = 'https://commondatastorage.googleapis.com/nativeclient-mirror'
 _LATEST_MANIFEST_URL = _NACL_MIRROR + '/nacl/nacl_sdk/naclsdk_manifest2.json'
 _NACL_SDK_ZIP_URL = _NACL_MIRROR + '/nacl/nacl_sdk/nacl_sdk.zip'
+_SRC_FILES = ['canned/host/nacl_sdk/download.py',
+              'canned/host/nacl_sdk/sdk_update.py']
+_DST_FILE_PATH = 'third_party/nacl_sdk/sdk_tools/'
 
 
 @build_common.with_retry_on_exception
@@ -38,6 +42,17 @@
   def post_update_work(self):
     # Update based on pinned manifest. This part can be as slow as 1-2 minutes
     # regardless of whether it is a fresh install or an update.
+
+    # Awful hack to avoid the certificates file used by NaCl SDK tools, as the
+    # current one causes an InvalidCertificateException. This will prevent
+    # NaCl SDK Tools from self-updating, as well as prevent the NaCl SDK Tools
+    # from using a now-invalid certificate file.
+    dst = os.path.join(build_common.get_arc_root(), _DST_FILE_PATH)
+    for f in _SRC_FILES:
+      src = os.path.join(build_common.get_arc_root(), f)
+      logging.info('%s: copying %s to %s', self.name, src, dst)
+      shutil.copy(src, dst)
+
     logging.info('%s: Updating naclsdk using manifest.', self.name)
     download_package_util.execute_subprocess([
         './naclsdk', 'update', '-U',