choosenim '#v0.17.0' fails
I installed choosenim on Ubuntu 16.04 using
`curl https://nim-lang.org/choosenim/init.sh -sSf | sh`

When I try to switch to 0.17.0 using
`choosenim '#v0.17.0'`

I get the following exception:
```
        ... lib/system.nim(408, 27) Error: type mismatch: got (type int)
        ... but expected one of: 
        ... proc high[T](x: T): T
```

(I tried to follow the "Let's Make a Game in Nim" video by Jez Impbox: 
https://www.youtube.com/watch?v=EwM1Z3WdqjM)

  