How do I rename a file in git that differs by case only?
As asked and answered on stackoverflow, there's an easier way to do this that doesn't involve making a new file system in a disk image file:

Move your existing file aside, commit that move, then move it back using the case you'd like it to maintain and commit. Done.

Example:

mv foo foo2
git add -A
git commit -m "renaming"
mv foo2 FOO
git add -A
git commit --amend -m "renamed foo to FOO"