It was 1.6.10 when they added that feature. I think the first release with it you could use any folder, not just src and then that caused some problems so they restricted it to the src subfolder only. So I don't know which of those releases 1.6.10 was, maybe the non-restrictive version was 1.6.9 or maybe it was 1.6.10 and the src restriction was added in 1.6.11.