Re: [PATCH] unpack-trees: don't update files flagged for deletion

David Turner [off-list ref] writes:

Don't update files in the worktree from cache entries which are
flagged with CE_WT_REMOVE.  This is fixes merges in sparse
checkouts.

s/This is/This/;

But more importantly, what is missing is "why" it is a good fix.
i.e. things like:

 - why is it wrong to update what is marked with CE_UPDATE bit to be
   updated in the working tree when CE_WT_REMOVE bit is on?

 - how that incorrect operation breaks which operation in what way?

 - how does the changed code fix that breakage?