None mentioned gitcrypt yet. I used it for 3 years, sharing password in a team of 4. A bit cumbersome to setup, but once you've been through the installation instructions, it just works.
Thank you for recommending Gitcrypt! I have been trying to remember the name because we have a couple of Git repos that need protecting. We need to encrypt them but I don't want it to be a big hassle to the developers that need to work with them.
https://github.com/shadowhand/git-encrypt