Hi,

Thanks for taking a look at it.
I have only tried it with argparse-1.4.0.

"I don't think add_mutually_exclusive_group and add_argument_group are designed to work together."

Yes, it really works strange in this case. I guess the framework should raise an exception which states that this use case is not supported, e.g. at the "serverGroup = mutexGroup.add_argument_group('serverGroup')
" line.