Log Message:
git-lfs: update to 2.12.0

Features
  config: optionally read .lfsconfig from the repository
  Support SHA-256 repositories
  allow Go 1.11 builds by using WaitStatus.ExitStatus()
  add --worktree option to install and uninstall commands
  Allow locking and unlocking non-existent files
Bugs
  docs/api/locking: add an explicit
  Fix hang when the user lacks permissions
  Don't mark unlocked files that aren't lockable as read-only
  git: consider full refspec when determining seen refs