'rustup toolchain link' doesn't seem to work under MSYS2

[japaric]

$ rustup toolchain link stage1 build/x86_64-pc-windows-gnu/stage1

$ echo $?
0

$ rustup default stage1
info: no toolchain installed for 'stage1'

$ rustup toolchain list
nightly-x86_64-pc-windows-gnu (default)
stage1

$ rustup toolchain remove stage1
info: no toolchain installed for 'stage1'

I think this is because the toolchain subcommand has special logic on Windows because one can pick between two toolchains: mingw and msvc (I think the logic implicitly appends a triple to the toolchain or something like that). Perhaps, that special logic shouldn't be used for custom toolchains.

cc @brson

[Diggsey]

Dup of #488 - it's fixed on master there just hasn't been a release since.

[japaric]

Oh, OK. That's why I didn't find any open issue about this. Closing then.