* 9356b79c updated res/grub2/core.img to GRUB 2.16, but left GRUB2_PACKAGE_VERSION at "2.14".
* Since this value is what the GRUB version detected on an ISO gets compared against, GRUB 2.14
based images would silently get the embedded 2.16 core.img (with no download being offered),
whereas GRUB 2.16 based images would prompt for an unnecessary core.img download.
* Closes#3066.