The Win Clang (dbg) builder on the GPU FYI waterfall is consistently failing the update_scripts step, with output:

error: bad signature
fatal: index file corrupt
error: bad signature
fatal: index file corrupt
error: bad signature
fatal: index file corrupt
Cannot rebase: You have unstaged changes.
error: bad signature
fatal: index file corrupt
Additionally, your index contains uncommitted changes.
Please commit or stash them.
Failed to update depot_tools.
Looking for .gclient starting from E:\b\build

Traceback (most recent call last):
  File "E:\b\depot_tools\gclient.py", line 2333, in <module>
    sys.exit(main(sys.argv[1:]))
  File "E:\b\depot_tools\gclient.py", line 2319, in main
    return dispatcher.execute(OptionParser(), argv)
  File "E:\b\depot_tools\subcommand.py", line 252, in execute
    return command(parser, args[1:])
  File "E:\b\depot_tools\gclient.py", line 2062, in CMDsync
    client = GClient.LoadCurrentConfig(options)
  File "E:\b\depot_tools\gclient.py", line 1384, in LoadCurrentConfig
    path = gclient_utils.FindGclientRoot(os.getcwd(), options.config_filename)
  File "E:\b\depot_tools\gclient_utils.py", line 608, in FindGclientRoot
    exec(FileRead(entries_filename), scope)
TypeError: expected string without null bytes

Build log:
https://build.chromium.org/p/chromium.gpu.fyi/builders/GPU%20Win%20Clang%20Builder%20%28dbg%29/builds/2673