From 7d00281b2bd1c7d91775ee97534f949a7bc0fa8f Mon Sep 17 00:00:00 2001
From: Daniel Tschinder <daniel.tschinder@researchgate.net>
Date: Fri, 3 Mar 2017 20:48:35 +0100
Subject: [PATCH] =?UTF-8?q?Don=E2=80=99t=20add=20duplicate=20entries=20to?=
 =?UTF-8?q?=20map?=
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---
 experimental/babel-preset-env/scripts/build-data.js | 1 +
 1 file changed, 1 insertion(+)

diff --git a/experimental/babel-preset-env/scripts/build-data.js b/experimental/babel-preset-env/scripts/build-data.js
index deba362443..fd16232fd0 100644
--- a/experimental/babel-preset-env/scripts/build-data.js
+++ b/experimental/babel-preset-env/scripts/build-data.js
@@ -69,6 +69,7 @@ const invertedEqualsEnv = Object.keys(envs)
           // that newer ones have
           if (!isNaN(equalsVersion) && equalsVersion <= version) {
             if (!a[equals]) a[equals] = [];
+            if (a[equals].indexOf(b) >= 0) return;
             a[equals].push(b);
           }
         });