Fix 'No data to report' error
Fix 'No data to report' error

Remove 2 unnecessary commands in 'testenv:cover' of tox.ini.
HTML coverage reports can be generated in 'cover' directory
by 'python setup.py testr --coverage' only
without the removed commands.

Change-Id: Ib9539f845aad29269a9cb07db719b22e35f7bbeb
Closes-Bug: #1613256

alaski/nova,phenoxim/nova,sebrandon1/nova,Juniper/nova,vmturbo/nova,cloudbase/nova,mikalstill/nova,gooddata/openstack-nova,klmitch/nova,openstack/nova,mikalstill/nova,klmitch/nova,sebrandon1/nova,rahulunair/nova,vmturbo/nova,jianghuaw/nova,alaski/nova,vmturbo/nova,mahak/nova,klmitch/nova,cloudbase/nova,openstack/nova,rajalokan/nova,vmturbo/nova,Juniper/nova,mahak/nova,jianghuaw/nova,rajalokan/nova,rajalokan/nova,rajalokan/nova,rahulunair/nova,hanlind/nova,gooddata/openstack-nova,phenoxim/nova,mahak/nova,gooddata/openstack-nova,gooddata/openstack-nova,hanlind/nova,mikalstill/nova,jianghuaw/nova,hanlind/nova,sebrandon1/nova,openstack/nova,Juniper/nova,Juniper/nova,jianghuaw/nova,klmitch/nova,cloudbase/nova,rahulunair/nova