See an example: https://uberchromegw.corp.google.com/i/chromeos.chrome/builders/cyan-tot-chrome-pfq-informational/builds/4016

selected error message:
[0:01:59] Checked out 0164974ae14f7aab195c311664b4f306cbc7ddbe to a detached HEAD. Before making any commits
in this repo, you should use 'git checkout <branch>' to switch to
an existing branch or use 'git checkout origin -b <branch>' to
create a new branch for your work.
----------------------------------------
Error: 1> dependency url must be either a string, None, or From() instead of dict
sync_chrome: Unhandled exception:
Traceback (most recent call last):
  File "/b/c/cbuild/repository/chromite/bin/sync_chrome", line 168, in <module>
    DoMain()
  File "/b/c/cbuild/repository/chromite/bin/sync_chrome", 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/sync_chrome.py", line 72, in main
    SyncChrome(gclient_path, options)
  File "/b/c/cbuild/repository/chromite/scripts/sync_chrome.py", line 48, in SyncChrome
    gclient.Sync(gclient_path, options.chrome_root, reset=options.reset)
  File "/b/c/cbuild/repository/chromite/lib/gclient.py", line 258, in Sync
    return cros_build_lib.RunCommand(cmd, cwd=cwd, **run_args)
  File "/b/c/cbuild/repository/chromite/lib/cros_build_lib.py", line 653, in RunCommand
    raise RunCommandError(msg, cmd_result)
chromite.lib.cros_build_lib.RunCommandError: return code: 1; command: /b/rr/tmpV4kiYV/w/depot_tools/gclient sync --with_branch_heads --with_tags --reset --force --delete_unversioned_trees --nohooks --verbose
cmd=['/b/rr/tmpV4kiYV/w/depot_tools/gclient', 'sync', '--with_branch_heads', '--with_tags', '--reset', '--force', '--delete_unversioned_trees', '--nohooks', '--verbose'], cwd=/b/c/cbuild/repository/.cache/distfiles/target-master/chrome-src-internal
11:40:11: WARNING: Command failed with retriable error.
return code: 1; command: /b/c/cbuild/repository/chromite/bin/sync_chrome --reset --internal --revision 0164974ae14f7aab195c311664b4f306cbc7ddbe /b/c/cbuild/repository/.cache/distfiles/target-master/chrome-src-internal
cmd=['/b/c/cbuild/repository/chromite/bin/sync_chrome', '--reset', '--internal', '--revision', '0164974ae14f7aab195c311664b4f306cbc7ddbe', '/b/c/cbuild/repository/.cache/distfiles/target-master/chrome-src-internal'], cwd=/b/c/cbuild/repository