Contributor graph working correctly?

Are we sure that the contributor graph is working correctly? Is it supposed to show everyone?

I am asking because https://gitlab.com/gitlab-org/gitlab-ce/graphs/master is quite different from the result of git shortlog --no-merges -6000 -nse Especially only two people with 1 commit are shown on the contributor graph, while the shortlog command shows 120 people with 1 commit.