To update on GitHub:
hg clone https://hg.csswg.org/dev/apiclient/
cd apiclient/.hg
wget https://gist.githubusercontent.com/gsnedders/11e478549a2f9a0cba84766b9d101994/raw/git-mapfile
git clone --bare https://github.com/w3c/csswg-apiclient.git git
cd ..
hg bookmark -r default master
hg push git+ssh://git@github.com:w3c/csswg-apiclient.git