It is currently not possible to specify which OS version to use. This is because the current OS images are flasher images. Extracting the OS image from inside requires extra code, although there is ongoing discussion on whether the images will remain flasher images, or if they will be divided and available separately. Rather than write the code for extracting the image which is required to allow OS selection, instead we have opted to wait on the images being available separately which will make the implementation far easier and save us the time of adding in the mechanism temporarily.
It is currently not possible to specify which OS version to use. This is because the current OS images are flasher images. Extracting the OS image from inside requires extra code, although there is ongoing discussion on whether the images will remain flasher images, or if they will be divided and available separately. Rather than write the code for extracting the image which is required to allow OS selection, instead we have opted to wait on the images being available separately which will make the implementation far easier and save us the time of adding in the mechanism temporarily.