gbp clone and the pristine-tar branch

Hi,

I have a question following https://honk.sigxcpu.org/piki/development/debian_packages_in_git/ --

`gbp clone` will create the pristine-tar branch, right?

After initially cloning with gbp clone you can run gbp pull to update your debian, upstream and pristine-tar branches from the remote site. So the complete workflow for simple team maintenance looks like this:
# Initially clone the repo once
gbp clone git://git.debian.org/pkg-libvirt/gtk-vnc.git

But having done that, I'm still not getting the pristine-tar branch.

I tried,

gbp clone https://github.com/neurobin/shc.git

then

gbp clone --pristine-tar https://github.com/neurobin/shc.git

but in both case, I got:

$ git branch -v

* master 556fd7a release after fix #38

release 379c501 release after fix #38

and `gbp pull` is not helping either, as oppose to,

you can run gbp pull to update your debian, upstream and pristine-tar branches

$ gbp pull

gbp:info: Fetching from default remote for each branch

gbp:info: Branch 'master' is already up to date.

$ gbp pull --all

gbp:info: Fetching from default remote for each branch

gbp:info: Branch 'master' is already up to date.

gbp:info: Branch 'release' is already up to date.

$ apt-cache policy git-buildpackage

git-buildpackage:

Installed: 0.9.9

Candidate: 0.9.9

Version table:

*** 0.9.9 100

50 http://cdn-fastly.deb.debian.org/debian unstable/main amd64 Packages

100 /var/lib/dpkg/status

0.8.12.2 500

500 http://cdn-fastly.deb.debian.org/debian stretch/main amd64 Packages

What I'm missing?

How can I get the pristine tarball from upstream?

thx

tong