Unsupported architecture: : "Asset prebuilt-.tar.gz not found

Attempting to follow: https://gitlab.com/gitlab-org/gitlab-ci-multi-runner/blob/master/docs/install/docker.md

results in the following:

This is on CentOS Linux release 7.2.1511 using Docker version 1.9.1, build ab77bde/1.9.1

Checking for builds... received                     runner=cbdb8e1f
gitlab-ci-multi-runner 1.3.0 (f9b3437)              build=21 runner=cbdb8e1f
Using Docker executor with image ruby:2.2 ...       build=21 runner=cbdb8e1f
ERROR: Failed to create container volume for /cache Unsupported architecture: : "Asset prebuilt-.tar.gz not found"  build=21 runner=cbdb8e1f
ERROR: Failed to create container volume for /builds/btaylor Unsupported architecture: : "Asset prebuilt-.tar.gz not found"  build=21 runner=cbdb8e1f
ERROR: Build failed: Unsupported architecture: : "Asset prebuilt-.tar.gz not found"  build=21 runner=cbdb8e1f
21 Submitting build to coordinator... ok            runner=cbdb8e1f

sudo docker run --name gitlab-runner --restart always \
  -v /var/run/docker.sock:/var/run/docker.sock:Z \
  --volume /srv/gitlab-runner:/etc/gitlab-runner:Z \
  gitlab/gitlab-runner:latest