Is this the most recent version:
OS + version:

Repo sync from source on 6/4/2018
Building locally on my Ubuntu 18.04 box

CPU architecture (32-bit / 64-bit): 64

What steps will reproduce the problem?

I am trying to build a Chromium browser for use with my local Chromium OS build by follow the instructions here:

https://chromium.googlesource.com/chromiumos/docs/+/master/simple_chrome_workflow.md

After this command:

cros chrome-sdk --board=$BOARD --log-level=info

I get a python backtrace ending with:
<snip>
...
 File "/home/duboisj/chromium/src/third_party/chromite/lib/cros_build_lib.py", line 182, in <genexpr>
    return ' '.join(ShellQuote(arg) for arg in cmd)
  File "/home/duboisj/chromium/src/third_party/chromite/lib/cros_build_lib.py", line 83, in ShellQuote
    s = s.encode('utf-8')
"UnicodeDecodeError: 'ascii' codec can't decode byte 0xe2 in position 1441: ordinal not in range(128)"

This appears right after a message:

 21:52:42: INFO: Installing Goma.

It looks to me like the real problem is that the script is trying this:

curl https://clients5.google.com/cxx-compiler-service/download/downloadurl

but failing with a 401 Unauthorized error (the python string that fails appears to be a short HTML blob saying basically 'permission denied')

The complete output / backtrace I get is:

duboisj@duboisj-ubuntu:~/chromium$ !293
cros chrome-sdk --board=amd64-generic --log-level=debug
21:52:42: DEBUG: Cache dir lookup.
21:52:42: DEBUG: Configured cache_dir to '/home/duboisj/chromium/.cros_cache'
21:52:42: DEBUG: Read LKGM version from /home/duboisj/chromium/src/chromeos/CHROMEOS_LKGM: 10748.0.0
21:52:42: INFO: Installing Goma.
21:52:42: INFO: RunCommand: curl https://clients5.google.com/cxx-compiler-service/download/downloadurl
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100  1616  100  1616    0     0   6029      0 --:--:-- --:--:-- --:--:--  6029
21:52:42: DEBUG: ending retries with error: <type 'exceptions.UnicodeDecodeError'>('ascii' codec can't decode byte 0xe2 in position 1441: ordinal not in range(128))
21:52:42: ERROR: cros chrome-sdk failed before completing.
cros: Unhandled exception:
Traceback (most recent call last):
  File "/home/duboisj/chromium/src/third_party/chromite/bin/cros", line 169, in <module>
    DoMain()
  File "/home/duboisj/chromium/src/third_party/chromite/bin/cros", line 165, in DoMain
    commandline.ScriptWrapperMain(FindTarget)
  File "/home/duboisj/chromium/src/third_party/chromite/lib/commandline.py", line 911, in ScriptWrapperMain
    ret = target(argv[1:])
  File "/home/duboisj/chromium/src/third_party/chromite/scripts/cros.py", line 66, in main
    code = _RunSubCommand(subcommand)
  File "/home/duboisj/chromium/src/third_party/chromite/scripts/cros.py", line 51, in _RunSubCommand
    return subcommand.Run()
  File "/home/duboisj/chromium/src/third_party/chromite/cli/cros/cros_chrome_sdk.py", line 1151, in Run
    goma_dir, goma_port = self._FetchGoma()
  File "/home/duboisj/chromium/src/third_party/chromite/cli/cros/cros_chrome_sdk.py", line 1081, in _FetchGoma
    '--output', self._GOMA_TGZ])
  File "/home/duboisj/chromium/src/third_party/chromite/lib/retry_util.py", line 404, in RunCurl
    sleep=3, backoff_factor=1.6, *args, **kwargs)
  File "/home/duboisj/chromium/src/third_party/chromite/lib/retry_util.py", line 353, in RunCommandWithRetries
    return RetryCommand(cros_build_lib.RunCommand, max_retry, *args, **kwargs)
  File "/home/duboisj/chromium/src/third_party/chromite/lib/retry_util.py", line 325, in RetryCommand
    return GenericRetry(ShouldRetry, max_retry, functor, *args, **kwargs)
  File "/home/duboisj/chromium/src/third_party/chromite/lib/retry_util.py", line 244, in GenericRetry
    return _run()
  File "/home/duboisj/chromium/src/third_party/chromite/lib/retry_util.py", line 177, in _Wrapper
    ret = func(*args, **kwargs)
  File "/home/duboisj/chromium/src/third_party/chromite/lib/retry_util.py", line 243, in _run
    return functor(*args, **kwargs)
  File "/home/duboisj/chromium/src/third_party/chromite/lib/cros_build_lib.py", line 587, in RunCommand
    logging.log(debug_level, 'RunCommand: %s', CmdToStr(cmd))
  File "/home/duboisj/chromium/src/third_party/chromite/lib/cros_build_lib.py", line 182, in CmdToStr
    return ' '.join(ShellQuote(arg) for arg in cmd)
  File "/home/duboisj/chromium/src/third_party/chromite/lib/cros_build_lib.py", line 182, in <genexpr>
    return ' '.join(ShellQuote(arg) for arg in cmd)
  File "/home/duboisj/chromium/src/third_party/chromite/lib/cros_build_lib.py", line 83, in ShellQuote
    s = s.encode('utf-8')
UnicodeDecodeError: 'ascii' codec can't decode byte 0xe2 in position 1441: ordinal not in range(128)

The python string which fails appears to contain a small HTML document informing me of a 401 Error because I don't have permission to download Goma.  In this thread:

https://groups.google.com/a/chromium.org/forum/#!topic/chromium-dev/sYZe7uS9E9Q

Mike F. said that a failed Goma download should not cause the cros chrome-sdk command to fail.