Index: src/wp-admin/install.php
===================================================================
--- src/wp-admin/install.php	(revision 27158)
+++ src/wp-admin/install.php	(working copy)
@@ -78,8 +78,9 @@
  */
 function display_setup_form( $error = null ) {
 	global $wpdb;
-	$user_table = ( $wpdb->get_var("SHOW TABLES LIKE '$wpdb->users'") != null );
 
+	$user_table = ( $wpdb->get_var( "SHOW TABLES LIKE '$wpdb->users'" ) != null );
+
 	// Ensure that Blogs appear in search engines by default
 	$blog_public = 1;
 	if ( ! empty( $_POST ) )
@@ -189,6 +190,7 @@
 			wp_die( $wpdb->error->get_error_message() );
 
 		display_header();
+
 		// Fill in the data we gathered
 		$weblog_title = isset( $_POST['weblog_title'] ) ? trim( wp_unslash( $_POST['weblog_title'] ) ) : '';
 		$user_name = isset($_POST['user_name']) ? trim( wp_unslash( $_POST['user_name'] ) ) : '';
@@ -196,7 +198,14 @@
 		$admin_password_check = isset($_POST['admin_password2']) ? wp_unslash( $_POST['admin_password2'] ) : '';
 		$admin_email  = isset( $_POST['admin_email']  ) ?trim( wp_unslash( $_POST['admin_email'] ) ) : '';
 		$public       = isset( $_POST['blog_public']  ) ? (int) $_POST['blog_public'] : 0;
-		// check e-mail address
+
+		$user_table = ( $wpdb->get_var( "SHOW TABLES LIKE '$wpdb->users'" ) != null );
+		if ( '' === $user_name && $user_table ) {
+			$admin = get_users( array( 'role' => 'administrator', 'count' => 1 ) );
+			$user_name = current( $admin )->user_login;
+		}
+
+		// Check e-mail address
 		$error = false;
 		if ( empty( $user_name ) ) {
 			// TODO: poka-yoke