Onionoo docker image create fails as we are still on master

Step 13/16 : RUN cd /srv/onionoo.torproject.org/ && git clone --recursive https://gitlab.torproject.org/tpo/network-health/metrics/onionoo.git  && cd onionoo && mkdir -p out && git checkout main && ant fetch-metrics-lib && ant resolve && ant war && cp generated/dist/onionoo-*-dev.jar onionoo-latest.jar && cp generated/dist/onionoo-*-dev.war onionoo-latest.war
 ---> Running in 0f1fbccc3399
Cloning into 'onionoo'...
Submodule 'src/build' (https://gitlab.torproject.org/tpo/metrics/base.git) registered for path 'src/build'
Cloning into '/srv/onionoo.torproject.org/onionoo/src/build'...
Submodule path 'src/build': checked out 'c5d7511a7300dd535d368ccb3390b52bff453534'
error: pathspec 'main' did not match any file(s) known to git