commit 7b30c661d8e6d7ca7991bfe1f5da09cca806ca22
Author: Christian Weiske <cweiske@cweiske.de>
Date:   Mon Feb 2 20:53:40 2015 +0100

    Fix oEmbed discovery for URLs with encoded entities
    
    Fixes #31213.

diff --git src/wp-includes/class-oembed.php src/wp-includes/class-oembed.php
index e5bc4a7..4862039 100644
--- src/wp-includes/class-oembed.php
+++ src/wp-includes/class-oembed.php
@@ -352,7 +352,7 @@ class WP_oEmbed {
 					$atts = shortcode_parse_atts( $link );
 
 					if ( !empty($atts['type']) && !empty($linktypes[$atts['type']]) && !empty($atts['href']) ) {
-						$providers[$linktypes[$atts['type']]] = $atts['href'];
+						$providers[$linktypes[$atts['type']]] = htmlspecialchars_decode($atts['href']);
 
 						// Stop here if it's JSON (that's all we need)
 						if ( 'json' == $linktypes[$atts['type']] )