Starting with 2.9.0~rc1, we are merging the signed upstream tags as
upstream, instead of using the tarball that doesn’t ship tests.

# Example to import upstream 2.10.0 version
version=2.10.0
# We still use the upstream branch to drop the .gitattributes file from upstream
gbp import-ref --upstream-tag=v%\(version%~%-\)s -u$version --debian-branch=upstream
gbp import-ref --upstream-tree=BRANCH -u$version
