Re: [PATCH v2 0/4] Integrate the sparse index with 'git apply' and interactive add, checkout, and reset

> Updates in v2
> =============
>
> Thanks for the careful review from Elijah and the pointer from Phillip, we
> have these changes:
>
>  1. The tests no longer have different expansion behaviors for 'git add -p'
>     and 'git add -i' due to partially-expanded indexes on disk.
>  2. We now test 'git checkout -p' and 'git reset -p'.
>  3. 'git reset -p' needed some changes to the builtin (similar to 'git add')
>     to be fast.

>  2:  63caae87634 ! 2:  0a2752721d0 git add: make -p/-i aware of sparse index
>      @@ Commit message
>
>           It turns out that control flows out of cmd_add() in the interactive
>           cases before the lines that confirm that the builtin is integrated with
>      -    the sparse index. We need to move that earlier to ensure it prevents a
>      -    full index expansion on read.
>      +    the sparse index.
>
>      -    Add more test cases that confirm that these interactive add options work
>      -    with the sparse index. One interesting aspect here is that the '-i'
>      -    option avoids expanding the sparse index when a sparse directory exists
>      -    on disk while the '-p' option does hit the ensure_full_index() method.
>      -    This leaves some room for improvement, but this case should be atypical
>      -    as users should remain within their sparse-checkout.
>      +    Moving that integration point earlier in cmd_add() allows 'git add -p'
>      +    and 'git add -p' to operate without expanding a sparse index to a full
>      +    one.