bug to track gerrit flakes right now. If this happens again, escalate.

failed paladin:
https://luci-logdog.appspot.com/v/?s=chromeos%2Fbb%2Fchromeos%2Felm-
paladin%2F1127%2F%2B%2Frecipes%2Fsteps%2FCommitQueueSync%2F0%2Fstdout

happened in a run with a huge number of CLs, so we were sync'ing a lot: https://uberchromegw.corp.google.com/i/chromeos/builders/master-paladin/builds/12922
while sync'ing kernel.

fatal: git fetch_pack: expected ACK/NAK, got 'ERR internal server error'
fatal: The remote end hung up unexpectedly
fatal: git fetch_pack: expected ACK/NAK, got 'ERR internal server error'
fatal: The remote end hung up unexpectedly
error: Cannot fetch chromiumos/third_party/kernel
error: Exited sync due to fetch errors


14:23:23: ERROR: return code: 1; command: repo --time sync --force-sync '--cache-dir=/b/cros_git_cache' -n
cwd=/b/cbuild/internal_master
14:23:23: ERROR: <class 'chromite.cbuildbot.repository.SrcCheckOutException'>: return code: 1; command: repo --time sync --force-sync '--cache-dir=/b/cros_git_cache' -n
cwd=/b/cbuild/internal_master
Traceback (most recent call last):
  File "/b/build/slave/elm-paladin-master/build/chromite/lib/failures_lib.py", line 172, in wrapped_functor
    return functor(*args, **kwargs)
  File "/b/build/slave/elm-paladin-master/build/chromite/cbuildbot/stages/sync_stages.py", line 890, in PerformStage
    self.ManifestCheckout(new_manifest)
  File "/b/build/slave/elm-paladin-master/build/chromite/cbuildbot/stages/sync_stages.py", line 1212, in ManifestCheckout
    super(CommitQueueSyncStage, self).ManifestCheckout(next_manifest)
  File "/b/build/slave/elm-paladin-master/build/chromite/cbuildbot/stages/sync_stages.py", line 435, in ManifestCheckout
    self.repo.Sync(next_manifest)
  File "/b/build/slave/elm-paladin-master/build/chromite/cbuildbot/repository.py", line 517, in Sync
    raise SrcCheckOutException(err_msg)
SrcCheckOutException: return code: 1; command: repo --time sync --force-sync '--cache-dir=/b/cros_git_cache' -n