Steps to reproduce (on x86)
1. Set up a root folder for the iso using "mkdir -p root/boot/grub"
2. Create a file at root/boot/grub/grub.cfg with the following contents:
"
#
# Some comment
#

sleep 1000
" (for some reason "halt --no-apm" didn't work for me in qemu, also a bug perhaps?).
3. Create a grub image with grub-mkimage: "grub-mkimage -p root/boot/grub -c root/boot/grub/grub.cfg -o bin/grub.img -O i386-pc normal sleep"
4. "cat /usr/lib/grub/i386-pc/cdboot.img grub.img > root/grub.img".
5. Create an iso with "genisoimage -b grub.img -no-emul-boot -boot-load-size 4 -boot-info-table -o grub.iso root/".
6. Boot the iso on any x86 machine or emulator.

Expected behavior
The grub.cfg file should be parsed correctly and no warnings should show on startup.

Actual result
The comments are interpreted instead of ignored and GRUB2 throws warnings about how '#' isn't a command (as shown in the screenshot).

I should note that this doesn't happen if the image is created using grub-mkrescue.

The software I'm using is:

• GRUB 2.02~rc1
• mkisofs 3.02a07
• QEMU 2.8.0

all running on x86_64 GNU/Linux 4.10.2-1-ARCH. Packages described above are all from the Arch Linux repos.