testbot/build: Chdir to the Wine source directory before calling 'git apply'.

[Henri Verbeet]

On 5 December 2012 05:35, Francois Gouget <fgouget at codeweavers.com> wrote:
> The --directory option is not meant to specify where the Git repository lives.
> ---
>
> I'm not sure how it worked before. Maybe this use of the --directory
> option worked by chance but git changed and broke it.
>
Alternatively you could set GIT_DIR, although I'm not quite familiar
enough with the code to know if there's a reason to prefer one over
the other.