Timmy: tox -ecover fails

$ tox -e cover
cover create: /home/lichunlin/timmy/.tox/cover
cover installdeps: -r/home/lichunlin/timmy/test-requirements.txt
cover develop-inst: /home/lichunlin/timmy
cover installed: coverage==4.2,docutils==0.12,extras==1.0.0,fixtures==3.0.0,flake8==2.5.5,hacking==0.11.0,Jinja2==2.8,linecache2==1.0.0,MarkupSafe==0.23,mccabe==0.2.1,pbr==1.10.0,pep8==1.5.7,py==1.4.31,pyflakes==0.8.1,Pygments==2.1.3,pytest==3.0.5,pytest-runner==2.9,python-mimeparse==1.6.0,python-subunit==1.2.0,PyYAML==3.12,six==1.10.0,Sphinx==1.2.3,sphinx-argparse==0.1.15,testrepository==0.0.20,testscenarios==0.5.0,testtools==2.2.0,-e git+https://github.com/openstack/timmy.git@d038b827f32dd72affc1e2875fb7e57129c256ec#egg=timmy,traceback2==1.4.0,unittest2==1.1.0
cover runtests: PYTHONHASHSEED='4128183120'
cover runtests: commands[0] | python setup.py test --coverage --testr-args=
usage: setup.py [global_opts] cmd1 [cmd1_opts] [cmd2 [cmd2_opts] ...]
   or: setup.py --help [cmd1 cmd2 ...]
   or: setup.py --help-commands
   or: setup.py cmd --help

error: option --coverage not recognized
ERROR: InvocationError: '/home/lichunlin/timmy/.tox/cover/bin/python setup.py test --coverage --testr-args='
___________________________________________________________________________________________________ summary ___________________________________________________________________________________________________
ERROR: cover: commands failed