Ticket #45073: 45073.2.patch

Index: src/wp-admin/about.php
===================================================================
--- src/wp-admin/about.php      (revision 43913)
+++ src/wp-admin/about.php      (working copy)
@@ -24,9 +24,25 @@
                <h1><?php printf( __( 'Welcome to WordPress&nbsp;%s' ), $display_version ); ?></h1>
 
                <p class="about-text"><?php printf( __( 'Thank you for updating to the latest version! WordPress %s introduces a robust new content creation experience.' ), $display_version ); ?></p>
-               <p class="about-text">
-                       <a href="#classic-editor"><?php _e( 'Learn how to keep using the old editor.' ); ?></a>
-               </p>
+
+               <?php if (
+                       // Was the Gutenberg plugin installed before upgrading to 5.0.x?
+                       get_option( 'upgrade_500_was_gutenberg_active' ) == '1'  &&
+                       current_user_can( 'activate_plugins' ) &&
+                       // Has it not been reactivated since?
+                       is_plugin_inactive( 'gutenberg/gutenberg.php' ) &&
+                       // Is it still installed?
+                       file_exists( WP_PLUGIN_DIR . '/gutenberg/gutenberg.php' )
+               ) : ?>
+                       <div class="about-text" style="font-style:italic;">
+                               <?php printf( __( 'The Gutenberg plugin has been deactivated, as the features are now included in WordPress %1$s by default. If you\'d like to continue to test the upcoming changes in the WordPress editing experience, please %2$sreactivate the Gutenberg plugin%3$s.' ), $display_version, '<a href="' . esc_url( self_admin_url( 'plugins.php?s=gutenberg&plugin_status=all' ) ) . '">', '</a>' ); ?>
+                       </div>
+               <?php else : ?>
+                       <p class="about-text">
+                               <a href="#classic-editor"><?php _e( 'Learn how to keep using the old editor.' ); ?></a>
+                       </p>
+               <?php endif; ?>
+
                <div class="wp-badge"><?php printf( __( 'Version %s' ), $display_version ); ?></div>
 
                <h2 class="nav-tab-wrapper wp-clearfix">
Index: src/wp-admin/includes/upgrade.php
===================================================================
--- src/wp-admin/includes/upgrade.php   (revision 43913)
+++ src/wp-admin/includes/upgrade.php   (working copy)
@@ -1819,11 +1819,18 @@
  */
 function upgrade_500() {
        global $wp_current_db_version;
        if ( $wp_current_db_version < 43764 ) {
                // Allow bypassing Gutenberg plugin deactivation.
                if ( defined( 'GUTENBERG_USE_PLUGIN' ) && GUTENBERG_USE_PLUGIN ) {
                        return;
                }
+
+               $was_active = is_plugin_active( 'gutenberg/gutenberg.php' );
+               if ( $was_active ) {
+                       // FIXME: Leave until 501 or 510 to clean up.
+                       update_site_option( 'upgrade_500_was_gutenberg_active', '1' );
+               }
+
                deactivate_plugins( array( 'gutenberg/gutenberg.php' ), true );
        }
 }