One point of view is that the removal of the atomic increment is justified because the programmer cannot rely on the execution of the go routine that contains t

One point of view is that the removal of the atomic increment is justified because the programmer cannot rely on the execution of the go routine that contains the increment. If you add an explicit call to the scheduler the problem is fixed. However, the justification is a bit of a stretch and it looks like it will be changed back to old behavior by the go developers.