`-c` not working on case-insensitive systems like macOS

[erikw]

Command-line says more than words:

$ touch UPPERCASE
$ rename -c UPPERCASE
'UPPERCASE' not renamed: 'uppercase' already exists

This was on macOS 12.3.1 on a case-insensitive APFS filesystem.

It would be great if the lower case renaming would work natively. Currently I have to make a wrapper in my renaming script for macOS to rename to a temporary file.

A workaround currently exist by forcing an overwrite

$ rename -c -f UPPERCASE