From b369593cbdecd9e065adc9b553cc4d7530c90c0c Mon Sep 17 00:00:00 2001
From: Mike McQuaid <mike@mikemcquaid.com>
Date: Sat, 4 Nov 2017 16:31:18 +0000
Subject: [PATCH] utils: correctly handle empty user gem env.

---
 Library/Homebrew/utils.rb | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/Library/Homebrew/utils.rb b/Library/Homebrew/utils.rb
index 0c875a8ab5..1d16044dad 100644
--- a/Library/Homebrew/utils.rb
+++ b/Library/Homebrew/utils.rb
@@ -189,8 +189,11 @@ module Homebrew
 
   def install_gem_setup_path!(name, version = nil, executable = name)
     # Respect user's preferences for where gems should be installed.
-    ENV["GEM_HOME"] = ENV["HOMEBREW_GEM_HOME"].to_s
-    ENV["GEM_HOME"] = Gem.user_dir if ENV["GEM_HOME"].empty?
+    ENV["GEM_HOME"] = if ENV["HOMEBREW_GEM_HOME"].to_s.empty?
+      Gem.user_dir
+    else
+      ENV["HOMEBREW_GEM_HOME"]
+    end
     unless ENV["HOMEBREW_GEM_PATH"].to_s.empty?
       ENV["GEM_PATH"] = ENV["HOMEBREW_GEM_PATH"]
     end