fixtures: fix empty repository fixture .git (#171)
fixtures: fix empty repository fixture .git (#171)

Previous fixture for empty.git was created with clone without --bare.
That was not valid for push tests. Replaced with a .git created with
git init --bare.

fuchsia-mirror/third_party-github.com-src-d-go-git,go-git/go-git,src-d/go-git,alcortesm/go-git,src-d/go-git,mcuadros/go-git,go-git/go-git,fuchsia-mirror/third_party-github.com-src-d-go-git,mcuadros/go-git,alcortesm/go-git