Increase resilience if lookup var comes back with nil object

[cyberious]

This blows up on Windows 2003 as no interfaces show up in Facter.

has_interface.pp

$a = '192.168.0.15'
$o = has_interface_with('ipaddress', $a)
notice(inline_template('has_interface_with is <%= @o.inspect %>'))

puppet apply yields

Error: undefined method `split' for nil:NilClass at C:/has_interface.pp:2 on node xran6l3uabwistu.mydomain.com
Wrapped exception:
undefined method `split' for nil:NilClass
Error: undefined method `split' for nil:NilClass at C:/has_interface.pp:2 on node xran6l3uabwistu.mydomain.com

[cyberious]

http://projects.puppetlabs.com/issues/21518
Target 1.7.3 for facter update to fix Windows server 2003 Interface