Comment 6 for bug 1048710

This seems related, might even be the same, but fails with a different case/error message:

#-- begin code--
import argparse
import sys
parser = argparse.ArgumentParser()
parser.add_argument("--log-file", "-l", default=sys.stderr, type=argparse.FileType('a'))
args = parser.parse_args()
#-- end code--

$ python bin/test-broken.py
usage: test-broken.py [-h] [--log-file LOG_FILE]
test-broken.py: error: argument --log-file/-l: invalid FileType('a') value: <open file '<stderr>', mode 'w' at 0x7f201a0fc270>