From 562c941e1e3736d4f0c47f87c07c93d30cac0029 Mon Sep 17 00:00:00 2001
From: Andrey Sitnik <andrey@sitnik.ru>
Date: Mon, 25 Sep 2017 17:00:40 +0300
Subject: [PATCH] Fix for empty EXECJS_RUNTIME

---
 lib/execjs/runtimes.rb | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/lib/execjs/runtimes.rb b/lib/execjs/runtimes.rb
index 52dc3c9..ac6cd90 100644
--- a/lib/execjs/runtimes.rb
+++ b/lib/execjs/runtimes.rb
@@ -64,7 +64,9 @@ module ExecJS
     end
 
     def self.from_environment
-      if name = ENV["EXECJS_RUNTIME"]
+      env = ENV["EXECJS_RUNTIME"]
+      if env && !env.empty?
+        name = env
         raise RuntimeUnavailable, "#{name} runtime is not defined" unless const_defined?(name)
         runtime = const_get(name)