My work laptop was provisioned with a case-insensitive filesystem for some strange reason.

This makes renaming stuff in a git repo “fun”:

$mv README.md readme.md
mv: 'README.md' and 'readme.md' are the same file

Here’s a workaround for this problem:

# give the file a temp name
git mv README.md readme_temp.md
git com -m "Rename 1 of 2"

# then name it what you actually want to call it
git mv readme_temp.md readme.md
git com -m "Rename 2 of 2"

Solved!