Don't delete everything if there are no posts.

git-svn-id: https://develop.svn.wordpress.org/trunk@1207 602fd350-edb4-49c9-b593-d223f7449a82

wp-admin/users.php

@@ -138,6 +138,7 @@ case 'delete':
 		die(__('Can’t delete a user whose level is higher than yours.'));
 
 	$post_ids = $wpdb->get_col("SELECT ID FROM $tableposts WHERE post_author = $id");
+	if ($post_ids) {
 		$post_ids = implode(',', $post_ids);
 		
 		// Delete comments, *backs
@@ -152,7 +153,7 @@ case 'delete':
 		$wpdb->query("DELETE FROM $tableposts WHERE post_author = $id");
 		// FINALLY, delete user
 		$wpdb->query("DELETE FROM $tableusers WHERE ID = $id");
-	
+	}
 	header('Location: users.php?deleted=true');
 
 break;