Don't use deprecated module commands

The commands module was deprecated since version 2.6 and it has been
removed in Python 3. This patch uses processutils.trycmd method to
replace of deprecated module commands.
See http://docs.python.org/2/library/commands#module-commands

Closes-Bug: #1248216

Change-Id: Iee0b3cf59c738bfda9c5b2049a1853abbb6d16e0

openstack/common/db/sqlalchemy/test_migrations.py

@@ -16,8 +16,6 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-
-import commands
 import ConfigParser
 import os
 import urlparse
@@ -27,6 +25,7 @@
 
 from openstack.common import lockutils
 from openstack.common import log as logging
+from openstack.common import processutils
 from openstack.common import test
 
 LOG = logging.getLogger(__name__)
@@ -143,9 +142,10 @@ def tearDown(self):
         super(BaseMigrationTestCase, self).tearDown()
 
     def execute_cmd(self, cmd=None):
-        status, output = commands.getstatusoutput(cmd)
+        out, err = processutils.trycmd(cmd, shell=True, discard_warnings=True)
+        output = out or err
         LOG.debug(output)
-        self.assertEqual(0, status,
+        self.assertEqual('', err,
                          "Failed to run: %s\n%s" % (cmd, output))
 
     @lockutils.synchronized('pgadmin', 'tests-', external=True)