TestSimpleChromeWorkflow started failing early today in all builders.

The failures seem to be specific to running Simple Chrome with a local chroot; Simple Chrome from a chrome checkout using prebuilts seems to be working OK.

Output from: https://uberchromegw.corp.google.com/i/chromeos/builders/amd64-generic-chromium-pfq/builds/10532/steps/TestSimpleChromeWorkflow/logs/stdio

11:39:53: INFO: Running cidb query on pid 34677, repr(query) starts with <sqlalchemy.sql.expression.Update object at 0x7f8ddece9090>
Preconditions for the stage successfully met. Beginning to execute stage...
11:39:53: INFO: Running cidb query on pid 34677, repr(query) starts with <sqlalchemy.sql.expression.Update object at 0x7f8ddecf3cd0>
11:39:53: INFO: RunCommand: cros --log-level debug --cache-dir /tmp/cbuildbot-tmpmj5Egl/chrome-sdk-cacheJqH8Wk/cache chrome-sdk --board amd64-generic --cwd /b/c/cbuild/repository/.cache/distfiles/target-master/chrome-src/src --sdk-path /b/c/cbuild/repository/buildbot_archive/amd64-generic-chromium-pfq/R63-9902.0.0-rc1 --nostart-goma --gomadir /b/c/goma_client --chrome-src /b/c/cbuild/repository/.cache/distfiles/target-master/chrome-src/src -- true in /b/c/cbuild/repository
11:39:54: DEBUG: Configured cache_dir to '/tmp/cbuildbot-tmpmj5Egl/chrome-sdk-cacheJqH8Wk/cache'
11:39:54: DEBUG: RunCommand: curl --fail https://storage.googleapis.com/chromeos-mirror/gentoo/distfiles/gsutil_4.19.tar.gz -o /tmp/cbuildbot-tmpmj5Egl/chrome-sdk-cacheJqH8Wk/cache/common/staging/tarball-cacheYQHDwn/gsutil_4.19.tar.gz
11:39:54: DEBUG: RunCommand: tar -xpf /tmp/cbuildbot-tmpmj5Egl/chrome-sdk-cacheJqH8Wk/cache/common/staging/tarball-cacheYQHDwn/gsutil_4.19.tar.gz in /tmp/cbuildbot-tmpmj5Egl/chrome-sdk-cacheJqH8Wk/cache/common/staging/tarball-cacheYQHDwn/extract
11:39:54: DEBUG: Attempting to compile local crcmod for gsutil
11:39:54: DEBUG: RunCommand: python ./setup.py build --build-base /tmp/cbuildbot-tmpmj5Egl/chromite.gsutil.crcmodFvFpGe --build-platlib /tmp/cbuildbot-tmpmj5Egl/chromite.gsutil.crcmodFvFpGe in /tmp/cbuildbot-tmpmj5Egl/chrome-sdk-cacheJqH8Wk/cache/common/gsutil_4.19.tar.gz/gsutil/third_party/crcmod
11:39:54: INFO: Could not read /b/c/cbuild/repository/buildbot_archive/amd64-generic-chromium-pfq/R63-9902.0.0-rc1/metadata.json, falling back to /b/c/cbuild/repository/buildbot_archive/amd64-generic-chromium-pfq/R63-9902.0.0-rc1/partial-metadata.json
11:39:54: ERROR: cros chrome-sdk failed before completing.
cros: Unhandled exception:
Traceback (most recent call last):
  File "/b/c/cbuild/repository/chromite/bin/cros", line 168, in <module>
    DoMain()
  File "/b/c/cbuild/repository/chromite/bin/cros", line 164, in DoMain
    commandline.ScriptWrapperMain(FindTarget)
  File "/b/c/cbuild/repository/chromite/lib/commandline.py", line 910, in ScriptWrapperMain
    ret = target(argv[1:])
  File "/b/c/cbuild/repository/chromite/scripts/cros.py", line 65, in main
    code = _RunSubCommand(subcommand)
  File "/b/c/cbuild/repository/chromite/scripts/cros.py", line 50, in _RunSubCommand
    return subcommand.Run()
  File "/b/c/cbuild/repository/chromite/cli/cros/cros_chrome_sdk.py", line 1019, in Run
    toolchain_url=self.options.toolchain_url) as ctx:
  File "/usr/lib/python2.7/contextlib.py", line 17, in __enter__
    return self.gen.next()
  File "/b/c/cbuild/repository/chromite/cli/cros/cros_chrome_sdk.py", line 379, in Prepare
    self.toolchain_path, toolchain_url % {'target': target_tc})
KeyError: u'version'

@@@STEP_FAILURE@@@
11:39:54: ERROR: Traceback (most recent call last):
  File "/b/c/cbuild/repository/chromite/cbuildbot/stages/generic_stages.py", line 693, in Run
    self.PerformStage()
  File "/b/c/cbuild/repository/chromite/cbuildbot/stages/chrome_stages.py", line 296, in PerformStage
    self._BuildChrome(sdk_cmd, goma)
  File "/b/c/cbuild/repository/chromite/cbuildbot/stages/chrome_stages.py", line 243, in _BuildChrome
    sdk_cmd.Run(['true'])
  File "/b/c/cbuild/repository/chromite/cbuildbot/commands.py", line 2858, in Run
    cros_build_lib.RunCommand(cros_cmd, cwd=self.cwd, **run_args)
  File "/b/c/cbuild/repository/chromite/lib/cros_build_lib.py", line 653, in RunCommand
    raise RunCommandError(msg, cmd_result)
RunCommandError: return code: 1; command: cros --log-level debug --cache-dir /tmp/cbuildbot-tmpmj5Egl/chrome-sdk-cacheJqH8Wk/cache chrome-sdk --board amd64-generic --cwd /b/c/cbuild/repository/.cache/distfiles/target-master/chrome-src/src --sdk-path /b/c/cbuild/repository/buildbot_archive/amd64-generic-chromium-pfq/R63-9902.0.0-rc1 --nostart-goma --gomadir /b/c/goma_client --chrome-src /b/c/cbuild/repository/.cache/distfiles/target-master/chrome-src/src -- true
cmd=['cros', '--log-level', 'debug', '--cache-dir', '/tmp/cbuildbot-tmpmj5Egl/chrome-sdk-cacheJqH8Wk/cache', 'chrome-sdk', '--board', u'amd64-generic', '--cwd', '/b/c/cbuild/repository/.cache/distfiles/target-master/chrome-src/src', '--sdk-path', u'/b/c/cbuild/repository/buildbot_archive/amd64-generic-chromium-pfq/R63-9902.0.0-rc1', '--nostart-goma', '--gomadir', '/b/c/goma_client', '--chrome-src', '/b/c/cbuild/repository/.cache/distfiles/target-master/chrome-src/src', '--', 'true'], cwd=/b/c/cbuild/repository