Don't allow images to be set as featured image until they have been processed.

props kadamwhite. fixes #23317.

git-svn-id: http://core.svn.wordpress.org/trunk@23956 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/js/media-views.js

@@ -2428,6 +2428,11 @@
 				var requires = button.options.requires,
 					disabled = false;
 
+				// Prevent insertion of attachments if any of them are still uploading
+				disabled = _.some( selection.models, function( attachment ) {
+					return attachment.get('uploading') === true;
+				});
+
 				if ( requires.selection && selection && ! selection.length )
 					disabled = true;
 				else if ( requires.library && library && ! library.length )