I can’t reproduce this issue. I ran:
% cd golang-github-danverbraganza-varcaser
% git remote set-url origin git@salsa.debian.org:go-team/packages/golang-github-danverbraganza-varcaser.git
% gbp push --dry-run --verbose
gbp:debug: ['git', 'rev-parse', '--show-cdup']
gbp:debug: ['git', 'rev-parse', '--is-bare-repository']
gbp:debug: ['git', 'rev-parse', '--git-dir']
gbp:debug: ['git', 'symbolic-ref', 'HEAD']
gbp:debug: ['git', 'show-ref', 'refs/heads/master']
gbp:debug: ['git', 'config', 'branch.master.remote']
gbp:debug: ['git', 'tag', '-l', 'debian/0.0_git20151108.ce61ec4-1']
gbp:debug: ['git', 'tag', '-l', 'upstream/0.0_git20151108.ce61ec4']
gbp:debug: ['git', 'rev-parse', '--quiet', '--verify', 'upstream/0.0_git20151108.ce61ec4^{commit}']
gbp:debug: ['git', 'rev-parse', '--quiet', '--verify', 'refs/heads/upstream']
gbp:debug: ['git', 'show-ref', '--verify', 'refs/heads/pristine-tar']
gbp:debug: ['git', 'log', '--pretty=format:%H', '--no-merges', '--grep=pristine-tar .* golang-github-danverbraganza-varcaser_0.0~git20151108.ce61ec4.orig.tar.*', 'pristine-tar', '--']
gbp:debug: Found pristine-tar commit at 'c7fd7478967c22a31118cb40a66a4c45da6474af'
gbp:debug: ['git', 'rev-parse', '--quiet', '--verify', 'c7fd7478967c22a31118cb40a66a4c45da6474af^{commit}']
gbp:debug: ['git', 'rev-parse', '--quiet', '--verify', 'refs/heads/pristine-tar']
gbp:info: Dry-run: Pushing upstream/0.0_git20151108.ce61ec4 to origin
gbp:debug: ['git', 'push', 'origin', 'tag', 'upstream/0.0_git20151108.ce61ec4', '--dry-run']
gbp:info: Dry-run: Pushing refs/heads/upstream to origin:refs/heads/upstream
gbp:debug: ['git', 'push', 'origin', '--dry-run', 'refs/heads/upstream:refs/heads/upstream']
gbp:info: Dry-run: Pushing refs/heads/pristine-tar to origin:refs/heads/pristine-tar
gbp:debug: ['git', 'push', 'origin', '--dry-run', 'refs/heads/pristine-tar:refs/heads/pristine-tar']
Can you reproduce this with the steps I listed?
If yes, it might be a good idea to file a bug report against git-buildpackage.