Not sure that really works for git though... at least with regards to it's primary usage.

git isn't just a backup... it's about version control.

IE the point is if you know what you are doing, you realize this function isn't working in this edge case, you can search through and find out, when did this part of this file change... and what was it before, and it will basically find exactly that.

If you encrypted it so that git couldn't actually read the contents, then you basically reduced a crazy powerful tool, into a glorified dropbox. (IE yeah you could revert back to previous versions... but you'd basically be counting on your memory for what you changed when, if the git server can't read the files).