Revert allow_concurrency change for better testing. Retrieve_connection in two steps to avoid side-effect bug (yuk).

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@3745 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

activerecord/lib/active_record/base.rb

@@ -310,7 +310,7 @@ module ActiveRecord #:nodoc:
     # Determines whether or not to use a connection for each thread, or a single shared connection for all threads.
     # Defaults to false. Set to true if you're writing a threaded application.
     cattr_accessor :allow_concurrency
-    @@allow_concurrency = false
+    @@allow_concurrency = true
 
     # Determines whether to speed up access by generating optimized reader
     # methods to avoid expensive calls to method_missing when accessing

activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb

@@ -55,7 +55,8 @@ module ActiveRecord
           conn
         else
           # retrieve_connection sets the cache key.
-          active_connections[@active_connection_name] = retrieve_connection
+          conn = retrieve_connection
+          active_connections[@active_connection_name] = conn
         end
       end