LibSass interpolation bug

interpolation.scss

$name: "world";

// works:
.#{$name} {
  test: test;
}

// fails:
.-#{$name} {
  test: test;
}

// workaround:
.#{"-" + $name} {
  test: test;
}

// works:
.hello-#{$name} {
  test: test;
}