Re: [PATCH 5/5] diff: store graph prefix buf in git_graph struct

> Since we only need the strbuf when we are formatting graph padding, we
> can give ownership of the strbuf to the git_graph struct, letting us
> free it when that struct is no longer in use.
>
>  static const char *diff_output_prefix_callback(struct diff_options *opt, void *data)
>  {
>  	struct git_graph *graph = data;
> -	static struct strbuf msgbuf = STRBUF_INIT;
>  
>  	assert(opt);
>  
>  	if (!graph)
>  		return opt->line_prefix;
>  
> -	strbuf_reset(&msgbuf);