Support submodules when building from a gh repo
Support submodules when building from a gh repo

Docker-DCO-1.1-Signed-off-by: Song Gao <song@gao.io> (github: songgao)

ashfall/cli,Zebrilee/cli,redpanda/cli,cpuguy83/cli,thaJeztah/cli,docker/cli,e11137/cli,docker/cli,cpuguy83/cli,riyazdf/cli,Zebrilee/cli,allencloud/cli,thaJeztah/cli,ashfall/cli,allencloud/cli,redpanda/cli,dnephin/cli,dnephin/cli,riyazdf/cli,e11137/cli