I managed to get it working by skipping bootloader installation, and then booting a Debian Install CD in rescue mode.
If you run grub-install in chroot you get:
To fix this you need to install grub-pc, it seems it's not installed by default in the beta. So it's using grub with UEFI by default. Which fails on Qemu since it only supports BIOS with default settings.
As root in the chroot environment you need to run:
The developers should take a look at this and fix the problem