Re: [PATCH v8] diff.c: keep arrow(=>) on show_stats()'s shortened filename part to make rename visible

> "git diff -M --stat" can detect rename and show renamed file name like
> "foofoofoo => barbarbar".
>
> Before this commit, this output is shortened always by omitting left most
> part like "...foo => barbarbar". So, if the destination filename is too long,
> source filename putting left or arrow can be totally omitted like
> "...barbarbar", without including any of "foofoofoo =>".
> In such a case where arrow symbol is omitted, there is no way to know
> whether the file is renamed or existed in the original.
>
> Make sure there is always an arrow, like "...foo => ...bar".
>
> The output can contain curly braces('{','}') for grouping.
> So, in general, the output format is "<pfx>{<mid_a> => <mid_b>}<sfx>"
>
> To keep arrow("=>"), try to omit <pfx> as long as possible at first
> because later part or changing part will be the more important part.
> If it is not enough, shorten <mid_a>, <mid_b> trying to have the same
> maximum length.
> If it is not enough yet, omit <sfx>.
>
> Signed-off-by: Tsuneo Yoshioka <yoshiokatsuneo@gmail.com>
> Test-added-by: Thomas Rast <trast@inf.ethz.ch>
> ---