Python3 buffer extra byte??

[Dodo]

Let's consider this code:

#!/usr/bin/python3
import cgi, sys
print("Content-type:image/jpeg\n\n")
f = open("img.jpg","rb")
sys.stdout.flush()
sys.stdout.buffer.write( f.read() )
f.close()

I receive the file with one padding byte at the start of the file (0x0a)
http://www.1pix.org/multi/images/wg7zg58gsgbhc9cppo5i.jpg

Any idea why?

Dorian
(yes, this is the continuation of "CGI python 3 write RAW BINARY")