Don't cache option values while installing. See #12140.

git-svn-id: http://svn.automattic.com/wordpress/trunk@14502 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/functions.php

@@ -338,6 +338,7 @@ function get_option( $option, $default = false ) {
 			// Has to be get_row instead of get_var because of funkiness with 0, false, null values
 			if ( is_object( $row ) ) {
 				$value = $row->option_value;
+				if ( ! defined( 'WP_INSTALLING' ) )
 					wp_cache_add( $option, $value, 'options' );
 			} else { // option does not exist, so we must cache its non-existence
 				$notoptions[$option] = true;