Hack in get_sample_permalink() can cause filters like post_link, and pre_post_link to have inaccurate post_status in admin

[aubreypwd]

For context: ​https://github.com/aubreypwd/WordPress/issues/5

When editing a post (that is a draft) in the admin, add a filter to post_link you'll notice that the pass for get_sample_permalink() shows that $post->post_status is set incorrectly (un-truthfully) to publish.

This is because of a 12 year old block of code in get_sample_permalink():

// Hack: get_permalink() would return ugly permalink for drafts, so we will fake that our post is published.
if ( in_array( $post->post_status, array( 'draft', 'pending', 'future' ) ) ) {
	$post->post_status = 'publish';
	$post->post_name   = sanitize_title( $post->post_name ? $post->post_name : $post->post_title, $post->ID );
}

In order for post_link and even pre_post_link filters to pass accurate info about a post, the patch I have attached is my first attempt at ensuring get_sample_permalink() still gets the same result, while not affecting post_status. Obviously I tested this, but I still feel some more testing will need to be done.

[aubreypwd]

First pass at fixing this that does not modify post_status but does not affect the desired result (please test!).