Only set the `poster` attribute automatically for videos when the image does not match the default mime-type icon. `wp_prepare_attachment_for_js()` is used in multiple contexts. This context requires disambiguation.

See [27659].


Built from https://develop.svn.wordpress.org/trunk@27980


git-svn-id: http://core.svn.wordpress.org/trunk@27810 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/js/media-editor.js

@@ -189,7 +189,7 @@
 			shortcode = {};
 
 			if ( 'video' === type ) {
-				if ( attachment.image ) {
+				if ( attachment.image && -1 === attachment.image.src.indexOf( attachment.icon ) ) {
 					shortcode.poster = attachment.image.src;
 				}