Question: When inside a git repository in Powershell or CMD, issuing

`git mv * whatever`

will return

> 
> fatal: bad source, source=\*, destination=whatever
> 
> 
> 

This works fine when using MSYS (Git Bash).

Answer: 
As @PetSerAI said, the Windows command prompt and PowerShell will not expand the globing characters and it makes `git mv` fail.

Use a bash shell like MSYS instead.
This also happens when you "source" directory doesn't exist.