Place bundler loaded gems after -I and RUBYLIB

Previously, gems were being placed at the front of the LOAD_PATH. This
meant you couldn't override a gem by setting -I or RUBYLIB.

This patch places -I and RUBYLIB in front of loaded gems and matches the
behavior in RubyGems.

1 files changed, 11 insertions, 1 deletions

diff --git a/lib/bundler/runtime.rb b/lib/bundler/runtime.rb
index 6ef476b9dc..0b1e5f92b5 100644
--- a/lib/bundler/runtime.rb
+++ b/lib/bundler/runtime.rb
@@ -37,7 +37,17 @@ module Bundler
 
         Bundler.rubygems.mark_loaded(spec)
         load_paths = spec.load_paths.reject {|path| $LOAD_PATH.include?(path) }
-        $LOAD_PATH.unshift(*load_paths)
+
+        # See Gem::Specification#add_self_to_load_path (since RubyGems 1.8)
+        insert_index = Gem.load_path_insert_index
+
+        if insert_index
+          # Gem directories must come after -I and ENV['RUBYLIB']
+          $LOAD_PATH.insert(insert_index, *load_paths)
+        else
+          # We are probably testing in core, -I and RUBYLIB don't apply
+          $LOAD_PATH.unshift(*load_paths)
+        end
       end
 
       setup_manpath