Re: [PATCH] fix multiple issues in index-pack

> Since commit 9441b61dc5, two issues affected correct behavior of 
> index-pack:
> 
>  1) The real_type of a delta object is the 'real_type' of its base, not
>     the 'type' which can be a "delta type".  Consequence of this is a
>     corrupted pack index file which only needs to be recreated with a 
>     good index-pack command ('git verify-pack' will flag those).
> 
>  2( The code sequence:
> 
>         result->data = patch_delta(get_base_data(base), base->obj->size,
>                                    delta_data, delta_size, &result->size);
> 
>     has two issues of its own since base->obj->size should instead be
>     base->size as we want the size of the actual object data and not
>     the size of the delta object it is represented by.  Except that 
>     simply replacing base->obj->size with base->size won't make the
>     code more correct as the C language doesn't enforce a particular 
>     ordering for the evaluation of needed arguments for a function call,
>     hence base->size could be pushed on the stack before get_base_data()
>     which initializes base->size is called.
> 
> Signed-off-by: Nicolas Pitre <nico@cam.org>