Gitlab flow is broken due to `git read-tree --prefix=/`

[joao-fontenele]

Describe the bug

The fix applied in #53 needs to be applied for setting up gitlab projects

Steps to reproduce

run bash setup.bash --gitlab, and answer the questions

it will fail with a message similar to fatal: Invalid prefix, prefix cannot start with '/'

after applying a similar fix, it resolved the issue

Expected behavior

for the setup to work :)