Merge branch 'ds/restore-sparse-index' into jch

'git restore --staged' has been optimized to avoid unnecessarily expanding
the sparse index when operating on paths within the sparse checkout
definition, by handling sparse directory entries at the tree level.

* ds/restore-sparse-index:
  restore: avoid sparse index expansion
  t1092: test 'git restore' with sparse index

diff --cc builtin/checkout.c
Simple merge