Allow running rails plugin new command inside rails application

railties/lib/rails/commands.rb

@@ -12,14 +12,19 @@ command = aliases[command] || command
 
 case command
 when 'generate', 'destroy', 'plugin'
-  require APP_PATH
-  Rails.application.require_environment!
+  if command == "plugin" && ARGV.first == "new"
+    require "rails/commands/plugin_new"
+  else
+    require APP_PATH
+    Rails.application.require_environment!
 
-  if defined?(ENGINE_PATH)
-    engine = Rails.application.railties.engines.find { |r| r.root.to_s == ENGINE_PATH }
-    Rails.application = engine
+    if defined?(ENGINE_PATH)
+      engine = Rails.application.railties.engines.find { |r| r.root.to_s == ENGINE_PATH }
+      Rails.application = engine
+    end
+
+    require "rails/commands/#{command}"
   end
-  require "rails/commands/#{command}"
 
 when 'benchmarker', 'profiler'
   require APP_PATH

railties/test/application/generators_test.rb

@@ -25,6 +25,12 @@ module ApplicationTests
       yield app_const.config
     end
 
+    test "allow running plugin new generator inside Rails app directory" do
+      FileUtils.cd rails_root
+      `./script/rails plugin new vendor/plugins/bukkits`
+      assert File.exist?(File.join(rails_root, "vendor/plugins/bukkits/test/dummy/config/application.rb"))
+    end
+
     test "generators default values" do
       with_bare_config do |c|
         assert_equal(true, c.generators.colorize_logging)