[git] Remove latest-items flag if git raw index is empty

[acs]

If we are fetching a git repository which we have already fetched it in the past (the repository exists in the perceval archive), if we pass the option latest-items to perceval it will only return the new commits that are not already in the archived cloned repository.

If the ocean raw index is empty and we want to get all commits, it won't work because it will only fetch new commits. The workaround now is to remove the archived repository. But the right approach is that if the git raw index is empty, don't use the latest-items param so perceval will return all the commits.