A URL like `example.com/2015/05/15/` generally resolves to the May 15, 2015 date
archive. But in certain cases, it could also be the permalink of a post with
the slug `'2015'`. When a conflict of this sort is detected, resolve to the post
instead of the archive.
URL conflicts of this sort should no longer occur for new posts; see [32647].
Props valendesigns, boonebgorges, Denis-de-Bernardy.
Fixes#5305.
git-svn-id: https://develop.svn.wordpress.org/trunk@32648 602fd350-edb4-49c9-b593-d223f7449a82
bb8999fb0e