make tox -e pylint only run pylint
make tox -e pylint only run pylint

Having the pylint environment run redundant commands just makes the
job take longer.

Change-Id: Ibb86b40e589d1b6f9c3af5901549d7aa5170e8c8
Signed-off-by: Doug Hellmann <0798ebecfb7bc4dfb9d0445c2fa030eb64e1fa1c@doughellmann.com>

openstack/trove,openstack/trove