Ensure temp files from RunCmd tests are removed

Signed-off-by: Michael Hanselmann <hansmi@google.com>
Reviewed-by: Iustin Pop <iustin@google.com>

test/ganeti.utils_unittest.py

@@ -245,6 +245,7 @@ class TestRunCmd(testutils.GanetiTestCase):
 
   def tearDown(self):
     shutil.rmtree(self.fifo_tmpdir)
+    testutils.GanetiTestCase.tearDown(self)
 
   def testOk(self):
     """Test successful exit code"""