Origin for each line in nextboot.init from check-in 5062c9b6fc:

5062c9b6fc 2019-10-19    1: # vim:ft=make:
5062c9b6fc 2019-10-19    2: 
5062c9b6fc 2019-10-19    3: nextboot: mount
5062c9b6fc 2019-10-19    4: .if exists(/boot/nextkernel)
5062c9b6fc 2019-10-19    5: 	: Removing nextboot setting.
5062c9b6fc 2019-10-19    6: 	rm -f /boot/nextkernel
5062c9b6fc 2019-10-19    7: .endif