wp_unique_post_slug does not work properly for hierarchical custom posts types

[chowmein]

Custom post types with hierarchy set to true, will still have a suffix appended to the slug if the post name is not unique.

Currently you will have to apply the 'hierarchical_post_types' filter to your custom post type. However, this should be done through register_post_type().

[nacin]

	$hierarchical_post_types = apply_filters( 'hierarchical_post_types', array( 'page' ) );

Should become:

	$hierarchical_post_types = get_post_types( 'hierarchical', true );

If we don't want to completely remove the filter, we should array_merge them.

[ryan]

(In [15348]) Use get_post_types() to create list of hierarchical post types. fixes #14079 for 3.1

[ryan]

(In [15349]) Use get_post_types() to create list of hierarchical post types. fixes #14079 for 3.0.1