SCSSPHP Compiler: parse error at `&} {` in mixins\_badge.scss and _badge.scss from bootstrap

If I try to compile my scss files which includes bootstrap (scss), then I've got an parse error

'parse error: failed at `&}` /mypath/scss/bootstrap/mixins/_badge.scss on line 5' (132 chars)

and

'parse error: failed at `&} {` /mypath/scss/bootstrap/_badge.scss on line 17' (128 chars)

It's working if I comment it out. I'm using the SCSSPHP Compiler.

mixins_badge.scss:

@at-root a#{&} {
    @include hover-focus {
      color: color-yiq($bg);
      background-color: darken($bg, 10%);
    }
}

and the same issue at _badge.scss:

@at-root a#{&} {
  @include hover-focus {
    text-decoration: none;
  }
}