OSTF test 'Check stack autoscaling' failed: "Time limit exceeded while waiting for terminating the 2nd instance..."

Reproduced on CI system test 'deploy_heat_simple_nova':
http://jenkins-product.srt.mirantis.net:8080/view/5.1_swarm/job/5.1_fuelmain.system_test.ubuntu.services_simple/63/
http://jenkins-product.srt.mirantis.net:8080/view/5.1_swarm/job/5.1_fuelmain.system_test.centos.services_simple/66/

        Scenario:
            1. Create cluster (Ubuntu/Centos simple, 1 controller, 1 compute, nova-network flat-dhcp)
            2. Deploy the cluster
            3. Verify heat services
            4. Register heat image
            5. Run OSTF platform tests

Result:

AssertionError: The following tests have not succeeded, while they must have passed: [u'Check stack autoscaling (fuel_health.tests.platform_tests.test_heat.HeatSmokeTests.test_autoscaling). Test status: failure, message: Time limit exceeded while waiting for terminating the 2nd instance per autoscaling alarm to finish. Please refer to OpenStack logs for more details.']

{u'build_id': u'2014-12-03_01-07-36', u'ostf_sha': u'64cb59c681658a7a55cc2c09d079072a41beb346', u'build_number': u'48', u'auth_required': True, u'nailgun_sha': u'500e36d08a45dbb389bf2bd97673d9bff48ee84d', u'production': u'docker', u'api': u'1.0', u'fuelmain_sha': u'7626c5aeedcde77ad22fc081c25768944697d404', u'astute_sha': u'ef8aa0fd0e3ce20709612906f1f0551b5682a6ce', u'feature_groups': [u'mirantis'], u'release': u'5.1.1', u'release_versions': {u'2014.1.3-5.1.1': {u'VERSION': {u'build_id': u'2014-12-03_01-07-36', u'ostf_sha': u'64cb59c681658a7a55cc2c09d079072a41beb346', u'build_number': u'48', u'api': u'1.0', u'nailgun_sha': u'500e36d08a45dbb389bf2bd97673d9bff48ee84d', u'production': u'docker', u'fuelmain_sha': u'7626c5aeedcde77ad22fc081c25768944697d404', u'astute_sha': u'ef8aa0fd0e3ce20709612906f1f0551b5682a6ce', u'feature_groups': [u'mirantis'], u'release': u'5.1.1', u'fuellib_sha': u'a3043477337b4a0a8fd166dc83d6cd5d504f5da8'}}}, u'fuellib_sha': u'a3043477337b4a0a8fd166dc83d6cd5d504f5da8'}