1 files changed, 17 insertions, 6 deletions

diff --git a/actionpack/lib/action_view/helpers/asset_tag_helpers/javascript_tag_helpers.rb b/actionpack/lib/action_view/helpers/asset_tag_helpers/javascript_tag_helpers.rb
index 6581e1d6f2..b9126af944 100644
--- a/actionpack/lib/action_view/helpers/asset_tag_helpers/javascript_tag_helpers.rb
+++ b/actionpack/lib/action_view/helpers/asset_tag_helpers/javascript_tag_helpers.rb
@@ -33,13 +33,21 @@ module ActionView
               all_asset_files = (collect_asset_files(custom_dir, ('**' if recursive), "*.#{extension}") - ['application']) << 'application'
               ((determine_source(:defaults, expansions).dup & all_asset_files) + all_asset_files).uniq
             else
-              expanded_sources = sources.collect do |source|
-                determine_source(source, expansions)
-              end.flatten
-              expanded_sources << "application" if sources.include?(:defaults) && File.exist?(File.join(custom_dir, "application.#{extension}"))
+              expanded_sources = sources.inject([]) do |list, source|
+                determined_source = determine_source(source, expansions)
+                update_source_list(list, determined_source)
+              end
+              add_application_js(expanded_sources, sources)
               expanded_sources
             end
           end
+
+          def add_application_js(expanded_sources, sources)
+            if sources.include?(:defaults) && File.exist?(File.join(custom_dir, "application.#{extension}"))
+              expanded_sources.delete('application')
+              expanded_sources << "application"
+            end
+          end
       end
 
 
@@ -59,7 +67,10 @@ module ActionView
           #     <script type="text/javascript" src="/javascripts/body.js"></script>
           #     <script type="text/javascript" src="/javascripts/tail.js"></script>
           def register_javascript_expansion(expansions)
-            JavascriptIncludeTag.expansions.merge!(expansions)
+            js_expansions = JavascriptIncludeTag.expansions
+            expansions.each do |key, values|
+              js_expansions[key] = (js_expansions[key] || []) | Array(values) if values
+            end
           end
         end
 
@@ -170,4 +181,4 @@ module ActionView
 
     end
   end
-end
\ No newline at end of file
+end