Index: wp-admin/admin-header.php
===================================================================
--- wp-admin/admin-header.php	(revision 28512)
+++ wp-admin/admin-header.php	(working copy)
@@ -50,6 +50,7 @@
 <title><?php echo $admin_title; ?></title>
 <?php
 
+wp_enqueue_style( 'open-sans' );
 wp_enqueue_style( 'colors' );
 wp_enqueue_style( 'ie' );
 wp_enqueue_script('utils');
Index: wp-admin/includes/media.php
===================================================================
--- wp-admin/includes/media.php	(revision 28512)
+++ wp-admin/includes/media.php	(working copy)
@@ -423,6 +423,7 @@
 <title><?php bloginfo('name') ?> &rsaquo; <?php _e('Uploads'); ?> &#8212; <?php _e('WordPress'); ?></title>
 <?php
 
+wp_enqueue_style( 'open-sans' );
 wp_enqueue_style( 'colors' );
 // Check callback name for 'media'
 if ( ( is_array( $content_func ) && ! empty( $content_func[1] ) && 0 === strpos( (string) $content_func[1], 'media' ) )
Index: wp-admin/includes/template.php
===================================================================
--- wp-admin/includes/template.php	(revision 28512)
+++ wp-admin/includes/template.php	(working copy)
@@ -1507,6 +1507,7 @@
 ?>
 <title><?php bloginfo('name') ?> &rsaquo; <?php echo $title ?> &#8212; <?php _e('WordPress'); ?></title>
 <?php
+wp_enqueue_style( 'open-sans' );
 wp_enqueue_style( 'colors' );
 ?>
 <script type="text/javascript">
Index: wp-admin/press-this.php
===================================================================
--- wp-admin/press-this.php	(revision 28512)
+++ wp-admin/press-this.php	(working copy)
@@ -290,7 +290,7 @@
 }
 die;
 }
-
+	wp_enqueue_style( 'open-sans' );
 	wp_enqueue_style( 'colors' );
 	wp_enqueue_script( 'post' );
 	add_thickbox();
Index: wp-includes/class-wp-admin-bar.php
===================================================================
--- wp-includes/class-wp-admin-bar.php	(revision 28512)
+++ wp-includes/class-wp-admin-bar.php	(working copy)
@@ -59,6 +59,7 @@
 		add_action('wp_head', $header_callback);
 
 		wp_enqueue_script( 'admin-bar' );
+		wp_enqueue_style( 'open-sans' );
 		wp_enqueue_style( 'admin-bar' );
 
 		/**
Index: wp-includes/script-loader.php
===================================================================
--- wp-includes/script-loader.php	(revision 28512)
+++ wp-includes/script-loader.php	(working copy)
@@ -597,14 +597,14 @@
 	}
 
 	// Register a stylesheet for the selected admin color scheme.
-	$styles->add( 'colors', true, array( 'wp-admin', 'buttons', 'open-sans', 'dashicons' ) );
+	$styles->add( 'colors', true, array( 'wp-admin', 'buttons', 'dashicons' ) );
 
 	$suffix = SCRIPT_DEBUG ? '' : '.min';
 
 	// Admin CSS
-	$styles->add( 'wp-admin',           "/wp-admin/css/wp-admin$suffix.css", array( 'open-sans', 'dashicons' ) );
-	$styles->add( 'login',              "/wp-admin/css/login$suffix.css", array( 'buttons', 'open-sans', 'dashicons' ) );
-	$styles->add( 'install',            "/wp-admin/css/install$suffix.css", array( 'buttons', 'open-sans' ) );
+	$styles->add( 'wp-admin',           "/wp-admin/css/wp-admin$suffix.css", array( 'dashicons' ) );
+	$styles->add( 'login',              "/wp-admin/css/login$suffix.css", array( 'buttons', 'dashicons' ) );
+	$styles->add( 'install',            "/wp-admin/css/install$suffix.css", array( 'buttons' ) );
 	$styles->add( 'wp-color-picker',    "/wp-admin/css/color-picker$suffix.css" );
 	$styles->add( 'customize-controls', "/wp-admin/css/customize-controls$suffix.css", array( 'wp-admin', 'colors', 'ie', 'imgareaselect' ) );
 	$styles->add( 'customize-widgets',  "/wp-admin/css/customize-widgets$suffix.css", array( 'wp-admin', 'colors' ) );
@@ -618,7 +618,7 @@
 	$styles->add( 'open-sans', $open_sans_font_url );
 
 	// Includes CSS
-	$styles->add( 'admin-bar',      "/wp-includes/css/admin-bar$suffix.css", array( 'open-sans', 'dashicons' ) );
+	$styles->add( 'admin-bar',      "/wp-includes/css/admin-bar$suffix.css", array( 'dashicons' ) );
 	$styles->add( 'wp-auth-check',  "/wp-includes/css/wp-auth-check$suffix.css", array( 'dashicons' ) );
 	$styles->add( 'editor-buttons', "/wp-includes/css/editor$suffix.css", array( 'dashicons' ) );
 	$styles->add( 'media-views',    "/wp-includes/css/media-views$suffix.css", array( 'buttons', 'dashicons', 'wp-mediaelement' ) );