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