Ticket #17451: upgrade-notice.17451.diff

src/wp-admin/includes/update.php

@@ -325 +325 @@
                 } else {
                         printf( __( 'There is a new version of %1$s available. <a href="%2$s" class="thickbox" title="%3$s">View version %4$s details</a> or <a href="%5$s" class="update-link">update now</a>.' ), $plugin_name, esc_url( $details_url ), esc_attr( $plugin_name ), $r->new_version, wp_nonce_url( self_admin_url( 'update.php?action=upgrade-plugin&plugin=' ) . $file, 'upgrade-plugin_' . $file ) );
                 }
+
+                if ( isset( $plugin_data['upgrade_notice'] ) ) {
+                        echo '<br />' . strip_tags( $plugin_data->update->upgrade_notice );
+                }
+
                 /**
                  * Fires at the end of the update message container in each
                  * row of the plugins list table.