Index: wp-admin/plugins.php
===================================================================
--- wp-admin/plugins.php	(revision 13330)
+++ wp-admin/plugins.php	(working copy)
@@ -155,7 +155,11 @@
 			}
 
 			@ini_set('display_errors', true); //Ensure that Fatal errors are displayed.
-			include(WP_PLUGIN_DIR . '/' . $plugin);
+			// Go back to "sandbox" scope so we get the same errors as before
+			function plugin_sandbox_scrape($plugin) {
+				include(WP_PLUGIN_DIR . '/' . $plugin);
+			}
+			plugin_sandbox_scrape($plugin);
 			do_action('activate_' . $plugin);
 			exit;
 			break;