When you see this error outside of github, here’s a remedy.
Got this from:
http://mapopa.blogspot.com/2009/10/git-insufficient-permission-for-adding.html
ssh me@myserver
cd repository/.git
sudo chmod -R g+ws *
sudo chgrp -R mygroup *
git config core.sharedRepository true
After this the git daemon should use the group file permissions when writing to .git/objects.