From 6e0ace1914f120fb24b2c1b648b08e4084011209 Mon Sep 17 00:00:00 2001
From: Francisco Giordano <frangio.1@gmail.com>
Date: Mon, 24 Sep 2018 20:38:33 -0300
Subject: [PATCH] make initializer modifier check if running in constructor

---
 contracts/Initializable.sol | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/contracts/Initializable.sol b/contracts/Initializable.sol
index a50149e5a..df1aa1e7b 100644
--- a/contracts/Initializable.sol
+++ b/contracts/Initializable.sol
@@ -29,7 +29,7 @@ contract Initializable {
    * @dev Modifier to use in the initializer function of a contract.
    */
   modifier initializer() {
-    require(initializing || !initialized, "Contract instance has already been initialized");
+    require(initializing || isConstructor() || !initialized, "Contract instance has already been initialized");
 
     bool wasInitializing = initializing;
     initializing = true;
@@ -39,4 +39,11 @@ contract Initializable {
 
     initializing = wasInitializing;
   }
+
+  /// @dev Returns true if and only if the function is running in the constructor
+  function isConstructor() private view returns (bool) {
+    uint cs;
+    assembly { cs := extcodesize(address) }
+    return cs == 0;
+  }
 }