Re: [PATCH] sparse-checkout: use fdopen_lock_file() instead of xfdopen()

> We do have to adjust the code a bit:
>
>   - we have to handle errors ourselves; we can just die(), since that's
>     what xfdopen() would have done (and we can even provide a more
>     specific error message).
>
>   - we no longer need to call fflush(); committing the lock-file
>     auto-closes it, which will now do the flush for us. As a bonus, this
>     will actually check that the flush was successful before renaming
>     the file into place. Let's likewise report when committing the lock
>     fails (rather than quietly returning success from the command).
>
>   - we can get rid of the local "fd" variable, since we never look at it
>     ourselves now