Windows: WinError with Windows filepath

[Wenzel]

[Artoria2e5]

It's an old powershell argument-passing bug. There's a pppretty long stream of issues etc, see PowerShell/PowerShell#15143 for one. IIRC the MS people didn't understand how command-passing works on Windows at first but came to their senses (but at that point I stopped caring so I may be wrong). The "Windows PowerShell", however, is never gonna be fixed because it's a frozen version.