Revert "PostgreSQL: introduce transaction_active? rather than trackin…

…g activity ourselves"

This commit conflicts with savepoint support.

This reverts commit 045713e.

Conflicts:

	activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb

activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb

@@ -529,44 +529,6 @@ def rollback_db_transaction
         execute "ROLLBACK"
       end
 
-      # ruby-pg defines Ruby constants for transaction status,
-      # ruby-postgres does not.
-      PQTRANS_IDLE = defined?(PGconn::PQTRANS_IDLE) ? PGconn::PQTRANS_IDLE : 0
-
-      # Check whether a transaction is active.
-      def transaction_active?
-        @connection.transaction_status != PQTRANS_IDLE
-      end
-
-      # Wrap a block in a transaction.  Returns result of block.
-      def transaction(start_db_transaction = true)
-        transaction_open = false
-        begin
-          if block_given?
-            if start_db_transaction
-              begin_db_transaction
-              transaction_open = true
-            end
-            yield
-          end
-        rescue Exception => database_transaction_rollback
-          if transaction_open && transaction_active?
-            transaction_open = false
-            rollback_db_transaction
-          end
-          raise unless database_transaction_rollback.is_a? ActiveRecord::Rollback
-        end
-      ensure
-        if transaction_open && transaction_active?
-          begin
-            commit_db_transaction
-          rescue Exception => database_transaction_rollback
-            rollback_db_transaction
-            raise
-          end
-        end
-      end
-
       def create_savepoint
         execute("SAVEPOINT #{current_savepoint_name}")
       end