Nano Pi, no non-ASCII characters on OLED display

[mackowiakp]

Bakebit OLED display was originally included in Friendly ARM Linux distro for NANO Pi. That is distro of Ubuntu/Debian 14.04 without X related functionality because this board does not contain GPU.
I try to print on display non-ASCII characters, included in TTF fonts provided by Bakebit. Based on included samples I wrote such code in Python2.7:

#!/usr/bin/env python
#-*- coding: utf-8 -*-  # Added for UTF-8 support
#
import bakebit_128_64_oled as oled
from PIL import Image
from PIL import ImageFont
from PIL import ImageDraw
import RPi.GPIO as GPIO
import time
import sys
import subprocess
import threading
import os
import socket
reload(sys)  # Added for UTF-8 support
sys.setdefaultencoding('utf-8')  # Added for UTF-8 support

global width
width=128
global height
height=64

# Reset OLED display
GPIO.setmode(GPIO.BOARD)
GPIO.setup(37, GPIO.IN, pull_up_down=GPIO.PUD_UP)
GPIO.setup(24, GPIO.OUT)
GPIO.output(24, True) 
time.sleep(0.1)
GPIO.output(24, False) 
time.sleep(0.1)
GPIO.output(24, True) 
time.sleep(0.2)
#
# End RESET display
#
oled.init()  #initialze SEEED OLED display
oled.setNormalDisplay()      #Set display to normal mode (i.e non-inverse mode)
oled.setHorizontalMode()

global image
image = Image.new('1', (width, height))
global draw
draw = ImageDraw.Draw(image)
global fontb24
fontb24 = ImageFont.truetype('DejaVuSansMono-Bold.ttf', 24);
global font14 
font14 = ImageFont.truetype('DejaVuSansMono.ttf', 14);
global smartFont
smartFont = ImageFont.truetype('DejaVuSansMono-Bold.ttf', 10);
global fontb14
fontb14 = ImageFont.truetype('DejaVuSansMono-Bold.ttf', 14);
global font11
font11 = ImageFont.truetype('DejaVuSansMono.ttf', 11);

draw.rectangle((0,0,width,height), outline=0, fill=0)
oled.drawImage(image)
draw.text((10, 0), "START SYSTEMU", font=fontb14, fill=255)
draw.text((23, 18), "AUTOMATYKI", font=fontb14, fill=255)
draw.text((0, 40), "SKRZYPOWA", font=fontb24, fill=255)
oled.drawImage(image)
time.sleep(5)
draw.rectangle((0,0,width,height), outline=0, fill=0)
oled.drawImage(image)

This code works OK. But if I change any letter to other, included in DejaVuSansMono but non-ASCII, random characters are display. If I print to console instead OLED, all characters are presented correctly. What I should change to get it working with full DejaVuSansMono character set?
Note, that I added all necessary commands to get python 2.7 working with UTF-8.