This repository includes the upstream Git history.

Setting up the second remote (once per clone):
git remote add upstream https://github.com/statsmodels/statsmodels

Importing a new upstream version:
git fetch upstream
gbp import-orig --upstream-branch=master --uscan --pristine-tar "--upstream-vcs-tag=v%(version)s" --debian-branch=debian

Remember that the source package the buildds see isn't a Git repo:
we (unlike upstream) can't use git as a clean command during the build.