Why does iotop cause python crash with error as "IOError [Errno 32] Broken pipe" ?

Issue

• iotop is crashing while use with pipe

$ sudo iotop -qqqb -n 1 |head -2
    1 be/4 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % init
    2 be/4 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % [kthreadd]
Traceback (most recent call last):
  File "/usr/sbin/iotop", line 16, in <module>
    main()
  File "/usr/lib/python2.6/site-packages/iotop/ui.py", line 559, in main
    main_loop()
  File "/usr/lib/python2.6/site-packages/iotop/ui.py", line 549, in <lambda>
    main_loop = lambda: run_iotop(options)
  File "/usr/lib/python2.6/site-packages/iotop/ui.py", line 445, in run_iotop
    return run_iotop_window(None, options)
  File "/usr/lib/python2.6/site-packages/iotop/ui.py", line 440, in run_iotop_window
    ui.run()
  File "/usr/lib/python2.6/site-packages/iotop/ui.py", line 120, in run
    self.process_list.duration)
  File "/usr/lib/python2.6/site-packages/iotop/ui.py", line 399, in refresh_display
    print l
IOError: [Errno 32] Broken pipe

• However it works fine when use as below

[root@test etc]# iotop -qqqb -n 1  | tail -5
 4603 be/4 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % console-kit-daemon --no-daemon
 4604 be/4 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % console-kit-daemon --no-daemon
 4605 be/4 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % console-kit-daemon --no-daemon
 4606 be/4 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % console-kit-daemon --no-daemon
 4607 be/4 root        0.00 B/s    0.00 B/s  0.00 %  0.00 % console-kit-daemon --no-daemon