Check if the lib is in the load path and requirable before attempting to activate the gem version

1 files changed, 12 insertions, 9 deletions

diff --git a/activesupport/lib/active_support/vendor.rb b/activesupport/lib/active_support/vendor.rb
index 8ba1dade91..9f464c8246 100644
--- a/activesupport/lib/active_support/vendor.rb
+++ b/activesupport/lib/active_support/vendor.rb
@@ -1,13 +1,16 @@
+def ActiveSupport.requirable?(file)
+  $LOAD_PATH.any? { |p| Dir.glob("#{p}/#{file}.*").any? }
+end
+
 [%w(builder 2.1.2), %w(i18n 0.1.3), %w(memcache-client 1.7.5), %w(tzinfo 0.3.13)].each do |lib, version|
-  # Try to activate a gem ~> satisfying the requested version first.
-  begin
-    gem lib, "~> #{version}"
-  # Use the vendored lib if the gem's missing or we aren't using RubyGems.
-  rescue LoadError, NoMethodError
-    # Skip if there's already a vendored lib already provided.
-    if $LOAD_PATH.grep(Regexp.new(lib)).empty?
-      # Push, not unshift, so the vendored lib is lowest priority.
-      $LOAD_PATH << File.expand_path("#{File.dirname(__FILE__)}/vendor/#{lib}-#{version}/lib")
+  # If the lib is not already requirable
+  unless ActiveSupport.requirable? lib
+    # Try to activate a gem ~> satisfying the requested version first.
+    begin
+      gem lib, "~> #{version}"
+      # Use the vendored lib if the gem's missing or we aren't using RubyGems.
+    rescue LoadError, NoMethodError
+      $LOAD_PATH.unshift File.expand_path("#{File.dirname(__FILE__)}/vendor/#{lib}-#{version}/lib")
     end
   end
 end