Just a bootstrapping problem, but maybe there's something simple that could make this easier to run. (This one is on a normal goobuntu machine).

scottmg@humid:/usr/local/google/work/cr/src$ git diff
diff --git a/tools/clang/scripts/package.py b/tools/clang/scripts/package.py
index 85840cdf008d..d88401012158 100755
--- a/tools/clang/scripts/package.py
+++ b/tools/clang/scripts/package.py
@@ -283,6 +283,8 @@ def main():
                  'lib/clang/*/lib/linux/*profile*',
                  'lib/clang/*/msan_blacklist.txt',
                  ])
+    # Also include the Fuchsia libclang_rt.*.a on Linux host.
+    want.append('lib/clang/*/lib/fuchsia/*libclang_rt.*')
   elif sys.platform == 'win32':
     want.extend(['lib/clang/*/lib/windows/clang_rt.asan*.dll',
                  'lib/clang/*/lib/windows/clang_rt.asan*.lib',
scottmg@humid:/usr/local/google/work/cr/src$ tools/clang/scripts/package.py
clang-298539-1
Desired toolchain revision 298539-1 is already available in Google Cloud Storage:
gs://chromium-browser-clang-staging/Linux_x64/clang-298539-1.tgz
gs://chromium-browser-clang-staging/Linux_x64/llvmgold-298539-1.tgz
scottmg@humid:/usr/local/google/work/cr/src$ LLVM_FORCE_HEAD_REVISION=1 tools/clang/scripts/package.py
svn: E155007: '/usr/local/google/work/cr/src/third_party/llvm' is not a working copy
Traceback (most recent call last):
  File "tools/clang/scripts/update.py", line 920, in <module>
    sys.exit(main())
  File "tools/clang/scripts/update.py", line 891, in main
    print GetSvnRevision(LLVM_DIR)
  File "tools/clang/scripts/update.py", line 170, in GetSvnRevision
    svn_info = subprocess.check_output('svn info ' + svn_repo, shell=True)
  File "/usr/lib/python2.7/subprocess.py", line 573, in check_output
    raise CalledProcessError(retcode, cmd, output=output)
subprocess.CalledProcessError: Command 'svn info /usr/local/google/work/cr/src/third_party/llvm' returned non-zero exit status 1
Traceback (most recent call last):
  File "tools/clang/scripts/package.py", line 369, in <module>
    sys.exit(main())
  File "tools/clang/scripts/package.py", line 175, in main
    expected_stamp = GetExpectedStamp()
  File "tools/clang/scripts/package.py", line 65, in GetExpectedStamp
    return subprocess.check_output(rev_cmd).rstrip()
  File "/usr/lib/python2.7/subprocess.py", line 573, in check_output
    raise CalledProcessError(retcode, cmd, output=output)
subprocess.CalledProcessError: Command '['/usr/bin/python', 'tools/clang/scripts/update.py', '--print-revision']' returned non-zero exit status 1