Bug#272136: countrychooser: db_go fails when choosing Arabic as language
Hmmm. The behavior I am seeing is somewhat different.
I can reproduce this both during normal installation and in qemu.
I have also made some screenshots of this.
1. Start d-i with linux26 debconf/priority=medium
2. Choose ar in languagechooser
3. Choose countrychooser
4. Countrylist is displayed correctly (translated countrynames) 
5. Choose "Go back"
6. Choose countrychooser again 
7. Countrychooser fails, I am returned to main menu and screen is garbled
The log (/var/log/syslog) shows:
- Process '/sbin/debian-installer' (pid ###) exited. Scheduling it for
- Starting pid ###, console /dev/vc/1: '/sbin/debian-installer'
Looking at output form ps, I see the following processes have new pid's:
- /bin/sh /sbin/debian-installer
- /usr/bin/bterm -f /unifont.bgf -l C.UTF-8 /lib/debian...
- debconf -o d-i /usr/bin/main-menu
I think the restart of bterm could explain the garbled screen.
8. Repair display by switching to vt2 and back (main menu is still in ar)
9. Choose countrychooser and everything repeats as from step 3.
I see something else that may be relevant if I scroll down in the country
1. I scroll using page down/page up, everything is OK.
2. I scroll all the way down using down arrow (there are two or three lines
'below the screen'), looks OK 
3. I scroll all the way up again using up arrow, looks OK
4. I press down arrow, last position of selection bar stays on top line 
5. I press down arrow, selection bar is again full length 
This might indicate there is something wrong with either the first, second,
last but one or last ('other') country name (my guess would be the second).