Index: src/wp-admin/plugin-editor.php
===================================================================
--- src/wp-admin/plugin-editor.php	(revision 38260)
+++ src/wp-admin/plugin-editor.php	(revision )
@@ -36,9 +36,7 @@
 	exit;
 }
 
-if ( $file ) {
-	$plugin = $file;
-} elseif ( empty( $plugin ) ) {
+if ( ! isset( $plugin ) || empty( $plugin ) ) {
 	$plugin = array_keys($plugins);
 	$plugin = $plugin[0];
 }
@@ -77,12 +75,12 @@
 				update_site_option( 'recently_activated', array( $file => time() ) + (array) get_site_option( 'recently_activated' ) );
 			}
 
-			wp_redirect(add_query_arg('_wpnonce', wp_create_nonce('edit-plugin-test_' . $file), "plugin-editor.php?file=$file&liveupdate=1&scrollto=$scrollto&networkwide=" . $network_wide));
+			wp_redirect(add_query_arg('_wpnonce', wp_create_nonce('edit-plugin-test_' . $file), "plugin-editor.php?file=$file&plugin=$plugin&liveupdate=1&scrollto=$scrollto&networkwide=" . $network_wide));
 			exit;
 		}
-		wp_redirect( self_admin_url("plugin-editor.php?file=$file&a=te&scrollto=$scrollto") );
+		wp_redirect( self_admin_url("plugin-editor.php?file=$file&plugin=$plugin&a=te&scrollto=$scrollto") );
 	} else {
-		wp_redirect( self_admin_url("plugin-editor.php?file=$file&scrollto=$scrollto") );
+		wp_redirect( self_admin_url("plugin-editor.php?file=$file&plugin=$plugin&scrollto=$scrollto") );
 	}
 	exit;