https://bugs.winehq.org/show_bug.cgi?id=12401
--- Comment #48 from Erich E. Hoover erich.e.hoover@gmail.com --- (In reply to Anastasius Focht from comment #47)
... 0009:fixme:ntdll:server_ioctl_file Unsupported ioctl 900a4 (device=9 access=0 func=29 method=0) error: unable to symlink C:\users\focht.rustup from C:\users\focht.multirust info: caused by: Request not supported. (os error 50) ...
I have been working on updating my patches for this and it does not appear that rust uses this feature. It looks like it uses hardlinks and this error only pops up every other run (when the file already exists).