Index: wp-admin/includes/post.php
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- wp-admin/includes/post.php	(revision 39414)
+++ wp-admin/includes/post.php	(revision )
@@ -1148,7 +1148,7 @@
 
 	// Filter query clauses to include filenames.
 	if ( isset( $q['s'] ) ) {
-		add_filter( 'posts_clauses', '_filter_query_attachment_filenames' );
+		add_filter( 'posts_clauses', '_filter_query_attachment_meta' );
 	}
 
 	return $q;
@@ -1171,7 +1171,7 @@
 	remove_filter( 'posts_clauses', __FUNCTION__ );
 
 	// Add a LEFT JOIN of the postmeta table so we don't trample existing JOINs.
-	$clauses['join'] .= " LEFT JOIN {$wpdb->postmeta} AS sq1 ON ( {$wpdb->posts}.ID = sq1.post_id AND sq1.meta_key = '_wp_attached_file' )";
+	$clauses['join'] .= " LEFT JOIN {$wpdb->postmeta} AS sq1 ON ( {$wpdb->posts}.ID = sq1.post_id AND ( sq1.meta_key = '_wp_attached_file' OR sq1.meta_key = '_wp_attachment_image_alt'  ) )";
 
 	$clauses['groupby'] = "{$wpdb->posts}.ID";