Bug#902881: [debian-installer] Cannot partition disk in Testing installer

[Alexander Kernozhitsky <sh200105@mail.ru>]

Package: debian-installer
Version: 20180610
Severity: grave

I tried to install Debian Testing on VirtualBox using a weekly build of Debian 
Installer. Everything went OK until the disk partitioning stage. In this 
stage, installer warned me that the kernel doesn't support LVM and I should 
load lvm-mod. Then, I didn't found an option to format a partition as Ext4 
filesystem. Automatical installation allowed to create an Ext4 root partition, 
but after writing the changes to disk it says something like "cannot mount /".

--- System information. ---
Architecture: 
Kernel:       Linux 4.16.0-2-amd64

Debian Release: buster/sid
  990 testing         ftp.by.debian.org 
  500 unstable        ftp.by.debian.org 

--- Package information. ---
Package's Depends field is empty.

Package's Recommends field is empty.

Package's Suggests field is empty.
-- 
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Alexander Kernozhitsky