Update the ModuleBuild.time_modified in case the format_mmd takes long time.

In case there is lot of components in a module build or there are some
networking issues and we need to retry the "git clone" commands, the
`format_mmd` method can take long time.

If it takes more than 10 minutes, the poller can produce fake event,
because it seems the module build is stuck. This is wrong, because
it would lead to another unexpected init handler call.

In this commit, the `format_mmd` updates the `ModuleBuild.time_modified`
method regularly to prevent poller from sending the unexpected fake
init message.

tests/test_utils/test_utils.py

@@ -630,6 +630,31 @@ class TestUtils:
             for pkg in mmd2.get_rpm_components().values():
                 assert set(pkg.get_arches().get()) == set(test_archs)
 
+    @patch('module_build_service.scm.SCM')
+    @patch('module_build_service.utils.submit.ThreadPool')
+    def test_format_mmd_update_time_modified(self, tp, mocked_scm):
+        with app.app_context():
+            init_data()
+            build = models.ModuleBuild.query.get(2)
+
+            async_result = mock.MagicMock()
+            async_result.ready.side_effect = [False, False, False, True]
+            tp.return_value.map_async.return_value = async_result
+
+            test_datetime = datetime(2019, 2, 14, 11, 11, 45, 42968)
+
+            testmodule_mmd_path = path.join(
+                BASE_DIR, '..', 'staged_data', 'testmodule.yaml')
+
+            mmd1 = Modulemd.Module().new_from_file(testmodule_mmd_path)
+            mmd1.upgrade()
+
+            with patch('module_build_service.utils.submit.datetime') as dt:
+                dt.utcnow.return_value = test_datetime
+                module_build_service.utils.format_mmd(mmd1, None, build, db.session)
+
+            assert build.time_modified == test_datetime
+
     def test_generate_koji_tag_in_nsvc_format(self):
         name, stream, version, context = ('testmodule', 'master', '20170816080815', '37c6c57')