Merge branch 'ws/sparse-check-rules'

"git sparse-checkout" command learns a debugging aid for the sparse
rule definitions.

* ws/sparse-check-rules:
  builtin/sparse-checkout: add check-rules command
  builtin/sparse-checkout: remove NEED_WORK_TREE flag

diff --cc builtin/sparse-checkout.c
Simple merge

diff --cc git.c
Simple merge