diff -r 3d4e9c994f10 -r a86126ab1dd4 wp/wp-admin/menu-header.php
--- a/wp/wp-admin/menu-header.php	Tue Oct 22 16:11:46 2019 +0200
+++ b/wp/wp-admin/menu-header.php	Tue Dec 15 13:49:49 2020 +0100
@@ -69,7 +69,7 @@
 	global $self, $parent_file, $submenu_file, $plugin_page, $typenow;
 
 	$first = true;
-	// 0 = menu_title, 1 = capability, 2 = menu_slug, 3 = page_title, 4 = classes, 5 = hookname, 6 = icon_url
+	// 0 = menu_title, 1 = capability, 2 = menu_slug, 3 = page_title, 4 = classes, 5 = hookname, 6 = icon_url.
 	foreach ( $menu as $key => $item ) {
 		$admin_is_parent = false;
 		$class           = array();
@@ -88,7 +88,7 @@
 			$submenu_items = $submenu[ $item[2] ];
 		}
 
-		if ( ( $parent_file && $item[2] == $parent_file ) || ( empty( $typenow ) && $self == $item[2] ) ) {
+		if ( ( $parent_file && $item[2] === $parent_file ) || ( empty( $typenow ) && $self === $item[2] ) ) {
 			if ( ! empty( $submenu_items ) ) {
 				$class[] = 'wp-has-current-submenu wp-menu-open';
 			} else {
@@ -108,7 +108,8 @@
 
 		$class     = $class ? ' class="' . join( ' ', $class ) . '"' : '';
 		$id        = ! empty( $item[5] ) ? ' id="' . preg_replace( '|[^a-zA-Z0-9_:.]|', '-', $item[5] ) . '"' : '';
-		$img       = $img_style = '';
+		$img       = '';
+		$img_style = '';
 		$img_class = ' dashicons-before';
 
 		if ( false !== strpos( $class, 'wp-menu-separator' ) ) {
@@ -152,10 +153,17 @@
 			$submenu_items = array_values( $submenu_items );  // Re-index.
 			$menu_hook     = get_plugin_page_hook( $submenu_items[0][2], $item[2] );
 			$menu_file     = $submenu_items[0][2];
-			if ( false !== ( $pos = strpos( $menu_file, '?' ) ) ) {
+			$pos           = strpos( $menu_file, '?' );
+
+			if ( false !== $pos ) {
 				$menu_file = substr( $menu_file, 0, $pos );
 			}
-			if ( ! empty( $menu_hook ) || ( ( 'index.php' != $submenu_items[0][2] ) && file_exists( WP_PLUGIN_DIR . "/$menu_file" ) && ! file_exists( ABSPATH . "/wp-admin/$menu_file" ) ) ) {
+
+			if ( ! empty( $menu_hook )
+				|| ( ( 'index.php' !== $submenu_items[0][2] )
+					&& file_exists( WP_PLUGIN_DIR . "/$menu_file" )
+					&& ! file_exists( ABSPATH . "/wp-admin/$menu_file" ) )
+			) {
 				$admin_is_parent = true;
 				echo "<a href='admin.php?page={$submenu_items[0][2]}'$class $aria_attributes>$arrow<div class='wp-menu-image$img_class'$img_style>$img</div><div class='wp-menu-name'>$title</div></a>";
 			} else {
@@ -164,10 +172,17 @@
 		} elseif ( ! empty( $item[2] ) && current_user_can( $item[1] ) ) {
 			$menu_hook = get_plugin_page_hook( $item[2], 'admin.php' );
 			$menu_file = $item[2];
-			if ( false !== ( $pos = strpos( $menu_file, '?' ) ) ) {
+			$pos       = strpos( $menu_file, '?' );
+
+			if ( false !== $pos ) {
 				$menu_file = substr( $menu_file, 0, $pos );
 			}
-			if ( ! empty( $menu_hook ) || ( ( 'index.php' != $item[2] ) && file_exists( WP_PLUGIN_DIR . "/$menu_file" ) && ! file_exists( ABSPATH . "/wp-admin/$menu_file" ) ) ) {
+
+			if ( ! empty( $menu_hook )
+				|| ( ( 'index.php' !== $item[2] )
+					&& file_exists( WP_PLUGIN_DIR . "/$menu_file" )
+					&& ! file_exists( ABSPATH . "/wp-admin/$menu_file" ) )
+			) {
 				$admin_is_parent = true;
 				echo "\n\t<a href='admin.php?page={$item[2]}'$class $aria_attributes>$arrow<div class='wp-menu-image$img_class'$img_style>$img</div><div class='wp-menu-name'>{$item[0]}</div></a>";
 			} else {
@@ -181,7 +196,7 @@
 
 			$first = true;
 
-			// 0 = menu_title, 1 = capability, 2 = menu_slug, 3 = page_title, 4 = classes
+			// 0 = menu_title, 1 = capability, 2 = menu_slug, 3 = page_title, 4 = classes.
 			foreach ( $submenu_items as $sub_key => $sub_item ) {
 				if ( ! current_user_can( $sub_item[1] ) ) {
 					continue;
@@ -189,14 +204,16 @@
 
 				$class           = array();
 				$aria_attributes = '';
+
 				if ( $first ) {
 					$class[] = 'wp-first-item';
 					$first   = false;
 				}
 
 				$menu_file = $item[2];
+				$pos       = strpos( $menu_file, '?' );
 
-				if ( false !== ( $pos = strpos( $menu_file, '?' ) ) ) {
+				if ( false !== $pos ) {
 					$menu_file = substr( $menu_file, 0, $pos );
 				}
 
@@ -204,15 +221,16 @@
 				$self_type = ! empty( $typenow ) ? $self . '?post_type=' . $typenow : 'nothing';
 
 				if ( isset( $submenu_file ) ) {
-					if ( $submenu_file == $sub_item[2] ) {
+					if ( $submenu_file === $sub_item[2] ) {
 						$class[]          = 'current';
 						$aria_attributes .= ' aria-current="page"';
 					}
 					// If plugin_page is set the parent must either match the current page or not physically exist.
 					// This allows plugin pages with the same hook to exist under different parents.
 				} elseif (
-					( ! isset( $plugin_page ) && $self == $sub_item[2] ) ||
-					( isset( $plugin_page ) && $plugin_page == $sub_item[2] && ( $item[2] == $self_type || $item[2] == $self || file_exists( $menu_file ) === false ) )
+					( ! isset( $plugin_page ) && $self === $sub_item[2] )
+					|| ( isset( $plugin_page ) && $plugin_page === $sub_item[2]
+						&& ( $item[2] === $self_type || $item[2] === $self || file_exists( $menu_file ) === false ) )
 				) {
 					$class[]          = 'current';
 					$aria_attributes .= ' aria-current="page"';
@@ -226,14 +244,19 @@
 
 				$menu_hook = get_plugin_page_hook( $sub_item[2], $item[2] );
 				$sub_file  = $sub_item[2];
-				if ( false !== ( $pos = strpos( $sub_file, '?' ) ) ) {
+				$pos       = strpos( $sub_file, '?' );
+				if ( false !== $pos ) {
 					$sub_file = substr( $sub_file, 0, $pos );
 				}
 
 				$title = wptexturize( $sub_item[0] );
 
-				if ( ! empty( $menu_hook ) || ( ( 'index.php' != $sub_item[2] ) && file_exists( WP_PLUGIN_DIR . "/$sub_file" ) && ! file_exists( ABSPATH . "/wp-admin/$sub_file" ) ) ) {
-					// If admin.php is the current page or if the parent exists as a file in the plugins or admin dir
+				if ( ! empty( $menu_hook )
+					|| ( ( 'index.php' !== $sub_item[2] )
+						&& file_exists( WP_PLUGIN_DIR . "/$sub_file" )
+						&& ! file_exists( ABSPATH . "/wp-admin/$sub_file" ) )
+				) {
+					// If admin.php is the current page or if the parent exists as a file in the plugins or admin directory.
 					if ( ( ! $admin_is_parent && file_exists( WP_PLUGIN_DIR . "/$menu_file" ) && ! is_dir( WP_PLUGIN_DIR . "/{$item[2]}" ) ) || file_exists( $menu_file ) ) {
 						$sub_item_url = add_query_arg( array( 'page' => $sub_item[2] ), $item[2] );
 					} else {