Fix indentation of Select nodes' macro interpolation

[HertzDevil]

Before:

select
when foo
  select
when bar
    1
else
    2
end

else
  select
when baz
    3
else
    4
end

end

After:

select
when foo
  select
  when bar
    1
  else
    2
  end
else
  select
  when baz
    3
  else
    4
  end
end