Without this, some tests will fail because they compare command output
of subprocesses (such as git) with $PWD -- but subprocesses have the
physical path as their working directory, whereas $PWD contains the
symlinked path. This fixes it.
Signed-off-by: Lea Wiemann <LeWiemann@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>