config are stored to global when using `bundle config set --local` more than once about bundler HOT 3 CLOSED

diff --git a/lib/bundler.rb b/lib/bundler.rb
index df345539c8..3d8d951086 100644
--- a/lib/bundler.rb
+++ b/lib/bundler.rb
@@ -285,7 +285,13 @@ module Bundler
 
     def app_config_path
       if app_config = ENV["BUNDLE_APP_CONFIG"]
-        Pathname.new(app_config).expand_path(root)
+        app_config_pathname = Pathname.new(app_config)
+
+        if app_config_pathname.absolute?
+          app_config_pathname
+        else
+          app_config_pathame.expand_path(root)
+        end
       else
         root.join(".bundle")
       end