Don't use the 'export NAME=value' in the test scripts.

Don't use the 'export NAME=value' in the test scripts.

This form is not portable across all shells, so replace instances of:

  export FOO=bar

with:

  FOO=bar
  export FOO

Signed-off-by: Bryan Donlan <bdonlan@fushizen.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>