Check reason of projects with failing migration

The two projects failed because they had imported template(s) (thus those files ends being 'untracked'). The script tries to add those untracked files to every commit in the history. But some files have already existed, which leads to an error.
The two projects have been fixed by removing the template(s), using Studio.

During the branch management D-Day test,
2 projects failed while migrating: ajubert-SANDBOX targuillere-SANDBOX

We need to assess the reason, and fix them if needed.

nuxeo@nos-prod-nuxeo01:/opt/migration/working_dir/logs/projects/ajubert-SANDBOX_migrate.log

• .metadata/imports untracked file to add to every commit: .metadata/imports/nuxeo-routing-default/org.nuxeo.studio.client.features.doctype.DocumentType
• the untracked file has already existed, rewriting the history would overwrite it.