I have a host which started to fail while gathering facts after the addition
of expanded memory facts in PR #9839:

Traceback (most recent call last):
  File "/home/ansible/.ansible/tmp/ansible-tmp-1422536976.05-133253824703289/setup", line 4278, in <module>
    main()
  File "/home/ansible/.ansible/tmp/ansible-tmp-1422536976.05-133253824703289/setup", line 137, in main
    data = run_setup(module)
  File "/home/ansible/.ansible/tmp/ansible-tmp-1422536976.05-133253824703289/setup", line 81, in run_setup
    facts = ansible_facts(module)
  File "/home/ansible/.ansible/tmp/ansible-tmp-1422536976.05-133253824703289/setup", line 4217, in ansible_facts
    facts.update(Hardware().populate())
  File "/home/ansible/.ansible/tmp/ansible-tmp-1422536976.05-133253824703289/setup", line 2339, in populate
    self.get_memory_facts()
  File "/home/ansible/.ansible/tmp/ansible-tmp-1422536976.05-133253824703289/setup", line 2375, in get_memory_facts
    'cached': memstats['swapcached']
KeyError: 'swapcached'

My problem host doesn't have SwapCached in /proc/meminfo. It may be better to
set defaults for these keys, since the values provided by /proc/meminfo can
change from version to version.