Comment by norberg

Hey. Google Keystone tech lead here. We are aware of the issue, and we've stopped the release. We're building a replacement that fixes the problem. In the meantime, to fix affected machines:

  sudo rm -rf /Library/Google/GoogleSoftwareUpdate/GoogleSoftwareUpdate.bundle
  sudo ln -F /private/var /var

This deletes the affected version of Keystone and reinstates the damaged /var symlink.

The version of Keystone packaged with Chrome is not affected by this bug, so allowing it to reinstall Keystone will not recreate the issue.