From becd2eea9dbb26afaae136eabc9c54e95f41a532 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Rytis=20Slatkevi=C4=8Dius?= <rytis.s@gmail.com>
Date: Wed, 23 Jan 2019 22:28:58 +0200
Subject: [PATCH] Do not allow page_head() to be called twice

error_page() calls page_head(), but there are instances of code that call error_page() having already called page_head() before, thus attempting to send headers twice and creating double page header.

Fixes #2960
---
 html/inc/util.inc | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/html/inc/util.inc b/html/inc/util.inc
index d5a3e28e9c..14d22c2569 100644
--- a/html/inc/util.inc
+++ b/html/inc/util.inc
@@ -243,6 +243,10 @@ function page_head(
     global $caching, $cache_control_extra, $did_page_head;
     global $is_login_page, $fixed_navbar;
 
+    if ($did_page_head) {
+        return;
+    }
+    
     $did_page_head = true;
     $url_base = url_base();