scarlet-chrome-pfq (experimental) [1] is failing in SyncChrome stage. Example failures at [2] and [3].

PFQ is still green since the bot is experimental, but these feel like real failures unrelated to bot's experimental nature.

Errors look like this:

  [0:00:37] Started.
  [0:00:54] error: object directory /b/git-cache/chromium.googlesource.com-a-chromium-src/objects does not exist; check .git/objects/info/alternates.
  [0:00:54] error: refs/heads/master does not point to a valid object!
  [0:00:54] error: refs/remotes/branch-heads/1000 does not point to a valid object!
  [0:00:54] error: refs/remotes/branch-heads/1001 does not point to a valid object!
  [0:00:54] error: refs/remotes/branch-heads/1002 does not point to a valid object!
  [0:00:54] error: refs/remotes/branch-heads/1003 does not point to a valid object!
  [0:00:54] error: refs/remotes/branch-heads/1004 does not point to a valid object!
  [0:00:54] error: refs/remotes/branch-heads/1005 does not point to a valid object!
  [0:00:54] error: refs/remotes/branch-heads/1006 does not point to a valid object!
  [0:00:54] error: refs/remotes/branch-heads/1007 does not point to a valid object!
  [0:00:54] error: refs/remotes/branch-heads/1008 does not point to a valid object!

1: https://uberchromegw.corp.google.com/i/chromeos/waterfall?builder=scarlet-chrome-pfq
2: https://uberchromegw.corp.google.com/i/chromeos/builders/scarlet-chrome-pfq/builds/812
3: https://uberchromegw.corp.google.com/i/chromeos/builders/scarlet-chrome-pfq/builds/813