Use the correct table name from fixture

Fixed a bug in fixtures.rb where the table name was incorrectly inferred from the fixture path which was ambiguously called "table_name" but was also used as the fixture name.
Now, the "correct" table name is taken from an instance variable.

activerecord/lib/active_record/fixtures.rb

@@ -486,8 +486,8 @@ def self.create_fixtures(fixtures_directory, table_names, class_names = {})
 
             # Cap primary key sequences to max(pk).
             if connection.respond_to?(:reset_pk_sequence!)
-              table_names.each do |table_name|
-                connection.reset_pk_sequence!(table_name.tr('/', '_'))
+              fixture_files.each do |ff|
+                connection.reset_pk_sequence!(ff.table_name)
               end
             end
           end