Fix another test that broke with the recent git-init-db update
Fix another test that broke with the recent git-init-db update

t5300-pack-object.sh test 8 expected to have to create the "pack"
directory itself, and was unhappy when it already existed.

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