t1020: Get rid of 'cd "$HERE"' at the start of each test
t1020: Get rid of 'cd "$HERE"' at the start of each test

To achieve that, all cd commands which weren't inside a subshell had to
be put into a new one.

Signed-off-by: Jens Lehmann <3a81d01482cca860e4077eb409d7db78ebdc6f24@web.de>
Signed-off-by: Junio C Hamano <a6723cc3f76163bf7adb636a73ac3b0ceb3e6b9b@pobox.com>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git