git clone --depth 1 --branch v6.1.0 https://github.com/mattermost/mattermost-server.git
ln -fs mattermost-server/vendor .
mkdir -p vendor/github.com/mattermost/mattermost-server
ln -fs `pwd`/mattermost-server vendor/github.com/mattermost/mattermost-server/v6
cat > vendor/modules.txt <<EOF
# github.com/mattermost/mattermost-server/v6 v6.1.0 => ./mattermost-server
## explicit
github.com/mattermost/mattermost-server/v6
EOF
touch $3