Description of problem:
Random crashes in poezio
Traceback (most recent call last):
  File "/usr/bin/poezio", line 4, in <module>
    main()
  File "/usr/lib64/python3.3/site-packages/poezio/poezio.py", line 51, in main
    cocore.main_loop()    # Refresh the screen, wait for user events etc
  File "/usr/lib64/python3.3/site-packages/poezio/core.py", line 535, in main_loop
    res = self.do_command(replace_line_breaks(char), False)
  File "/usr/lib64/python3.3/site-packages/poezio/core.py", line 663, in do_command
    return self.current_tab().on_input(key, raw)
  File "/usr/lib64/python3.3/site-packages/poezio/tabs.py", line 1366, in on_input
    self.input.do_command(key, raw=raw)
  File "/usr/lib64/python3.3/site-packages/poezio/windows.py", line 1537, in do_command
    res = self.key_func[key]()
  File "/usr/lib64/python3.3/site-packages/poezio/windows.py", line 1349, in key_backspace
    self.key_left()
  File "/usr/lib64/python3.3/site-packages/poezio/windows.py", line 1326, in key_left
    self.rewrite_text()
  File "/usr/lib64/python3.3/site-packages/poezio/windows.py", line 1600, in rewrite_text
    self.adjust_view_pos()
  File "/usr/lib64/python3.3/site-packages/poezio/windows.py", line 1638, in adjust_view_pos
    self.pos < self.view_pos + self.width)
AssertionError


Version-Release number of selected component (if applicable):
poezio-0.8.1-1.fc20.x86_64

How reproducible:
I don't know.

Steps to Reproduce:
I don't know

Actual results:
Random crashes

Expected results:
Normal works.