Fetch last value from sequence given currval may not be defined for the session (#103)

Author: cwjenkins

lib/database_cleaner/active_record/truncation.rb

@@ -224,7 +224,7 @@ def database_cleaner_table_cache
         def has_been_used?(table)
           return has_rows?(table) unless has_sequence?(table)
 
-          cur_val = select_value("SELECT currval('#{table}_id_seq');").to_i rescue 0
+          cur_val = select_value("SELECT last_value from #{table}_id_seq;").to_i
           cur_val > 0
         end