From 510704ffc44d6bec5e97b5aeef160542abf30f12 Mon Sep 17 00:00:00 2001
From: Kostas Manionis <kostasmanionis@users.noreply.github.com>
Date: Thu, 14 Sep 2017 01:53:02 +0300
Subject: [PATCH] fix(index): stricter check for `shouldExtract !==
 wasExtracted` (#605)

---
 src/index.js | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/index.js b/src/index.js
index f97c349f..69787f4b 100644
--- a/src/index.js
+++ b/src/index.js
@@ -149,7 +149,10 @@ class ExtractTextPlugin {
             let meta = module[NS];
             if (meta && (!meta.options.id || meta.options.id === id)) {
               const wasExtracted = Array.isArray(meta.content);
-              if (shouldExtract !== wasExtracted) {
+              // A stricter `shouldExtract !== wasExtracted` check to guard against cases where a previously extracted
+              // module would be extracted twice. Happens when a module is a dependency of an initial and a non-initial
+              // chunk. See issue #604
+              if (shouldExtract && !wasExtracted) {
                 module[`${NS}/extract`] = shouldExtract; // eslint-disable-line no-path-concat
                 compilation.rebuildModule(module, (err) => {
                   if (err) {