Restore compatibility with Python 2.6
Restore compatibility with Python 2.6

jennolsen84/PyTables,PyTables/PyTables,tp199911/PyTables,jack-pappas/PyTables,rabernat/PyTables,mohamed-ali/PyTables,mohamed-ali/PyTables,jack-pappas/PyTables,jack-pappas/PyTables,jennolsen84/PyTables,gdementen/PyTables,gdementen/PyTables,rabernat/PyTables,rdhyee/PyTables,mohamed-ali/PyTables,tp199911/PyTables,gdementen/PyTables,tp199911/PyTables,dotsdl/PyTables,avalentino/PyTables,jack-pappas/PyTables,dotsdl/PyTables,avalentino/PyTables,avalentino/PyTables,gdementen/PyTables,rdhyee/PyTables,andreabedini/PyTables,rdhyee/PyTables,andreabedini/PyTables,mohamed-ali/PyTables,FrancescAlted/PyTables,rabernat/PyTables,joonro/PyTables,FrancescAlted/PyTables,PyTables/PyTables,joonro/PyTables,dotsdl/PyTables,jennolsen84/PyTables,dotsdl/PyTables,rdhyee/PyTables,rabernat/PyTables,jennolsen84/PyTables,andreabedini/PyTables,PyTables/PyTables,andreabedini/PyTables,jack-pappas/PyTables,tp199911/PyTables,FrancescAlted/PyTables,joonro/PyTables,joonro/PyTables