Ruby 1.9 compat: use .to_a instead of .map which now returns an enumerator

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@8437 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

railties/lib/rails_generator/lookup.rb

@@ -139,7 +139,7 @@ module Rails
         private
           # Lookup and cache every generator from the source list.
           def cache
-            @cache ||= sources.inject([]) { |cache, source| cache + source.map }
+            @cache ||= sources.inject([]) { |cache, source| cache + source.to_a }
           end
 
           # Clear the cache whenever the source list changes.