How does one prevent Stretch from expanding the file system at boot time ? When you flash the new Stretch image (september 2017) on the SD card and boot the first time, it auto expands the file system on the whole SD card. Preventing this used to be possible under Jessie by removing the init= in cmdline.txt; there is no longer this option.
So how does one prevent this auto expand -- a 32GB card takes 40 minutes to copy to img format. I would love to keep the image to 6 or 8GB which is plenty for me, this would radically cut the time needed to backup and clone SD cards.