The problematic line is here: https://chromium.googlesource.com/infra/infra/+/4b231b956f3511b1b35379f8b6ce1eba341fb146/go/deps.py#466

On developer systems, "cipd" is available as "cipd.bat", not "cipd.exe". I think that this is also true on bots b/c "cipd_bootstrap_v2" generates a batch file for "cipd". Therefore, this should be safe to change to ".bat".

In the meantime, Windows users get a stack trace like this:
Searching for a bundle with dependencies in CIPD...
--------------------------------------------------------------------------------
CIPD package name:    infra/go-deps
CIPD package version: go_deps_lock:30a48567fbc38996da712cb9909e62695abbf64f
--------------------------------------------------------------------------------
Traceback (most recent call last):
  File "C:\Users\dnj\infra\infra\go\deps.py", line 811, in <module>
    sys.exit(main(sys.argv[1:]))
  File "C:\Users\dnj\infra\infra\go\deps.py", line 795, in main
    return install(workspace, opts.force, opts.update_out)
  File "C:\Users\dnj\infra\infra\go\deps.py", line 549, in install
    use_bundle = is_existing_bundle(workspace, pkg, ver)
  File "C:\Users\dnj\infra\infra\go\deps.py", line 494, in is_existing_bundle
    return cipd(workspace, ['resolve', pkg, '-version', ver], silent=True) == 0
  File "C:\Users\dnj\infra\infra\go\deps.py", line 475, in cipd
    stderr=subprocess.PIPE if silent else None)
  File "C:\Users\dnj\infra\depot_tools\python276_bin\lib\subprocess.py", line 709, in __init__
    errread, errwrite)
  File "C:\Users\dnj\infra\depot_tools\python276_bin\lib\subprocess.py", line 957, in _execute_child
    startupinfo)
WindowsError: [Error 2] The system cannot find the file specified
Traceback (most recent call last):
  File ".\go\env.py", line 101, in <module>
    main()
  File ".\go\env.py", line 83, in main
    deps_only=args.deps_only)
  File ".\go\bootstrap.py", line 617, in prepare_go_environ
    bootstrap(layout, logging.INFO)
  File ".\go\bootstrap.py", line 579, in bootstrap
    p, layout.toolset_root, force=toolset_updated)
  File ".\go\bootstrap.py", line 462, in update_vendor_packages
    subprocess.check_call(cmd, stdout=sys.stderr, env=env)
  File "C:\Users\dnj\infra\depot_tools\python276_bin\lib\subprocess.py", line 540, in check_call
    raise CalledProcessError(retcode, cmd)
subprocess.CalledProcessError: Command '['C:\\Users\\dnj\\infra\\depot_tools\\python276_bin\\python.exe', '-u', 'C:\\Users\\dnj\\infra\\infra\\go\\deps.py', '--workspace', 'C:\\Users\\dnj\\infra\\infra\\go', '--goroot', 'C:\\Users\\dnj\\
infra\\golang\\go', 'install', '--update-out', 'C:\\Users\\dnj\\infra\\infra\\go\\tmpx6yqus\\deps_updated.json']' returned non-zero exit status 1