Without this patch applied there is no easy way to append one array to
another. This is a problem because it is often desirable to join two
arrays without flattening the contents into a single, one dimensional
array.
This patch addresses the problem by adding a `concat()` function which
takes two arguments. The arguments will be concatenated together and a
new array returned to the caller.
Reviewed-by: Jeff McCune <jeff@puppetlabs.com>
