Merge branch 'vd/sparse-clean-etc' into en/present-despite-skipped

Merge branch 'vd/sparse-clean-etc' into en/present-despite-skipped

* vd/sparse-clean-etc:
  update-index: reduce scope of index expansion in do_reupdate
  update-index: integrate with sparse index
  update-index: add tests for sparse-checkout compatibility
  checkout-index: integrate with sparse index
  checkout-index: add --ignore-skip-worktree-bits option
  checkout-index: expand sparse checkout compatibility tests
  clean: integrate with sparse index
  reset: reorder wildcard pathspec conditions
  reset: fix validation in sparse index test