AttributeError: 'DeprecateAction' object has no attribute 'mdhelp'

python train.py Error:
python train.py -data OpenNMT/BPE/new/enta -save_model OpenNMT/BPE/new/enta1 -brnn -gpuid 0

Traceback (most recent call last):
File “train.py”, line 36, in
opt = parser.parse_args()
File “/usr/lib/python2.7/argparse.py”, line 1701, in parse_args
args, argv = self.parse_known_args(args, namespace)
File “/usr/lib/python2.7/argparse.py”, line 1733, in parse_known_args
namespace, args = self._parse_known_args(args, namespace)
File “/usr/lib/python2.7/argparse.py”, line 1939, in _parse_known_args
start_index = consume_optional(start_index)
File “/usr/lib/python2.7/argparse.py”, line 1879, in consume_optional
take_action(action, args, option_string)
File “/usr/lib/python2.7/argparse.py”, line 1807, in take_action
action(self, namespace, argument_values, option_string)
File “/home/rajivratn/nmt/OpenNMT-py/onmt/opts.py”, line 590, in call
help = self.help if self.mdhelp is not None else “”
AttributeError: ‘DeprecateAction’ object has no attribute ‘mdhelp’