Difference in tell results (1 for Python, 0 for pyfakefs)

[agroce]

import shutil
import pyfakefs.fake_filesystem
import os

ROOT_PATH = "/Volumes/ramdisk/test"

fs = pyfakefs.fake_filesystem.FakeFilesystem()
fs.CreateDirectory('/Volumes')
fs.CreateDirectory('/Volumes/ramdisk')
fs.CreateDirectory('/Volumes/ramdisk/test')
os0 = pyfakefs.fake_filesystem.FakeOsModule(fs)
opener0 = pyfakefs.fake_filesystem.FakeFileOpen(fs)

if False:
    os0 = os
    opener0 = open
    shutil.rmtree(ROOT_PATH)
    os.mkdir(ROOT_PATH)

component0 = "alpha" 
path0 = ROOT_PATH 
path0 += os.path.sep + component0 
bytes0 = 0 
bytes0 += 1 
file0 = opener0(path0,'a') 
file0.seek(bytes0) 
result = file0.tell() 
print result