[COVERAGE] Turn off coverage

We need to fix .coveragerc and turn off coverage in one patch, since
cover.sh scrip launch check for previous patch which contain uncompatible
with coverage 4.0 option.

Also, fix for floating bug is required.

Change-Id: I4cc49c01bc5bb633f08353762f963cb4343fc6cb
Partial-Bug: #1497897

.coveragerc

@@ -3,5 +3,4 @@ branch = True
 source = rally
 
 [report]
-ignore-errors = True
 precision = 3

tests/ci/cover.sh

@@ -15,6 +15,8 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+exit 0
+
 ALLOWED_EXTRA_MISSING=4
 
 show_diff () {

tests/unit/verification/test_tempest.py

@@ -263,7 +263,7 @@ class TempestInstallAndUninstallTestCase(BaseTestCase):
     @mock.patch(TEMPEST_PATH + ".tempest.subprocess.check_call")
     @mock.patch("shutil.copytree")
     @mock.patch(TEMPEST_PATH + ".tempest.Tempest._clone")
-    @mock.patch("os.path.exists", return_value=False)
+    @mock.patch(TEMPEST_PATH + ".tempest.os.path.exists", return_value=False)
     def test_install_failed(self, mock_exists, mock_tempest__clone,
                             mock_copytree, mock_check_call,
                             mock_tempest__install_venv,