cache: Create a temporary work directory per instance.
cache: Create a temporary work directory per instance.

Signed-off-by: mefyl <a639889f268ed9eb2c872c19b8505dfe978f8da6@gruntech.org>

dra27/jbuilder,janestreet/jbuilder,dra27/jbuilder,janestreet/jbuilder,janestreet/jbuilder,dra27/jbuilder,janestreet/jbuilder,janestreet/jbuilder,dra27/jbuilder,dra27/jbuilder,janestreet/jbuilder,dra27/jbuilder