"[ ] Discourage search engines from indexing this site". fixes #16416.

git-svn-id: https://develop.svn.wordpress.org/trunk@21851 602fd350-edb4-49c9-b593-d223f7449a82

wp-includes/formatting.php

@@ -2797,6 +2797,14 @@ function sanitize_option($option, $value) {
 			$value = preg_replace('/[^a-zA-Z0-9_-]/', '', $value); // strips slashes
 			break;
 
+		case 'blog_public':
+			// This is the value if the settings checkbox is not checked on POST. Don't rely on this.
+			if ( null === $value )
+				$value = 1;
+			else
+				$value = intval( $value );
+			break;
+
 		case 'date_format':
 		case 'time_format':
 		case 'mailserver_url':