Bug#852192: using boot_delay=500 renders system unbootable

[積丹尼 Dan Jacobson]

Package: src:linux
Version: 4.8.15-2

$ cat /proc/cmdline
BOOT_IMAGE=/boot/vmlinuz-4.8.0-2-amd64 
root=UUID=50c0e259-55bb-4fc0-867e-63160edef01f ro single 
systemd.log_level=debug systemd.log_target=kmsg log_buf_len=262144 enforcing=0 
panic=33 earlyprintk=vga
worked fine. But if boot_delay=500 is added to it,
all that happens is two lines are printed on the screen, and one has to
power cycle.