Grub install failed

Hi,

I tried to install Debian GNU/Hurd (20180220, 20180222 snapshot) to my 
notebook (via virtualbox) but towards the end of the installation the 
grub install always failed.
Then i tried install to another desktop machine (with no virtualbox), 
but i receive the same error..
I post a few console log, maybe help:
/var/lib/dpkg/info/grub-installer postinst: line 35: db_input not found
configuring 'grub-installer' failed with error code 1

-- 
Sztrepka Pál