-Ythrough-tasty doesn't work anymore

[smarter]

I don't know when this happened but it must be recent since I use it frequently:

Minimized code

class A

> run -Ythrough-tasty A.scala
Compiling from .scala sources
Compiling TASTY from .class sources
File does not exist: A
Failed compilation from TASTY
Compilation input: /home/smarter/opt/dotty/out/from-tasty-tmp6130131065886806267/from-source

[nicolasstucki]

It needs to be pass the .tasty file to the second step