Cache top fails

Bcc tools works fine, but when I run cachetop utility it gives following error

`Traceback (most recent call last):
File "./cachetop", line 254, in
curses.wrapper(handle_loop, args)
File "/usr/lib/python2.7/curses/wrapper.py", line 43, in wrapper
return func(stdscr, *args, **kwds)
File "./cachetop", line 229, in handle_loop
*stat, username=pwd.getpwuid(int(stat[1]))[0]
_curses.error: addstr() returned ERR`

But sometimes it works for a few seconds and gives the same error.

I've got 4.4.0-66-generic Ubuntu Xenial

Reproduce the failure by running the cachetop utility on Ubuntu Xenial, then inspect cachetop at line 229 where curses.addstr() reports the error. Determine the terminal or output condition that triggers the intermittent failure and verify that cachetop continues running without the curses error.

Written by the indexing model from the issue text.