diff --git a/README.rst b/README.rst
index 9d19c23..3d7c804 100644
--- a/README.rst
+++ b/README.rst
@@ -209,15 +209,9 @@
 Python 3.x
 ----------
 
-Starting during the Liberty release development cycle work began on enabling
-Tempest to run under both Python 2.7 and Python 3.4. Tempest strives to fully
-support running with Python 3.4 and newer. A gating unit test job was added to
-also run Tempest's unit tests under Python 3. This means that the Tempest
-code at least imports under Python 3.4 and things that have unit test coverage
-will work on Python 3.4. However, because large parts of Tempest are
-self-verifying there might be uncaught issues running on Python 3. So until
-there is a gating job which does a full Tempest run using Python 3 there
-isn't any guarantee that running Tempest under Python 3 is bug free.
+Starting during the Pike cycle Tempest has a gating CI job that runs tempest
+with Python 3. Any tempest release after 15.0.0 should fully support running
+under Python 3 as well as Python 2.7.
 
 Legacy run method
 -----------------
diff --git a/releasenotes/notes/add-tempest-run-combine-option-e94c1049ba8985d5.yaml b/releasenotes/notes/add-tempest-run-combine-option-e94c1049ba8985d5.yaml
new file mode 100644
index 0000000..73900ca
--- /dev/null
+++ b/releasenotes/notes/add-tempest-run-combine-option-e94c1049ba8985d5.yaml
@@ -0,0 +1,6 @@
+---
+features:
+  - |
+    Adds a new cli option to tempest run, --combine, which is used to indicate
+    you want the subunit stream output combined with the previous run's in
+    the testr repository
diff --git a/tempest/api/compute/servers/test_servers_negative.py b/tempest/api/compute/servers/test_servers_negative.py
index b22a434..1418b3f 100644
--- a/tempest/api/compute/servers/test_servers_negative.py
+++ b/tempest/api/compute/servers/test_servers_negative.py
@@ -176,7 +176,7 @@
 
         self.assertRaises(lib_exc.NotFound,
                           self.client.rebuild_server,
-                          server['id'], self.image_ref_alt)
+                          server['id'], self.image_ref)
 
     @test.related_bug('1660878', status_code=409)
     @test.attr(type=['negative'])
@@ -198,7 +198,7 @@
         self.assertRaises(lib_exc.NotFound,
                           self.client.rebuild_server,
                           nonexistent_server,
-                          self.image_ref_alt)
+                          self.image_ref)
 
     @test.attr(type=['negative'])
     @decorators.idempotent_id('fd57f159-68d6-4c2a-902b-03070828a87e')
diff --git a/tempest/api/identity/admin/v3/test_roles.py b/tempest/api/identity/admin/v3/test_roles.py
index b7b6596..9bee24a 100644
--- a/tempest/api/identity/admin/v3/test_roles.py
+++ b/tempest/api/identity/admin/v3/test_roles.py
@@ -15,11 +15,14 @@
 
 from tempest.api.identity import base
 from tempest.common.utils import data_utils
+from tempest import config
 from tempest.lib.common.utils import test_utils
 from tempest.lib import decorators
 from tempest.lib import exceptions as lib_exc
 from tempest import test
 
+CONF = config.CONF
+
 
 class RolesV3TestJSON(base.BaseIdentityV3AdminTest):
 
@@ -348,6 +351,15 @@
         # domain role to a global one
         self._create_implied_role(domain_role1['id'], self.role['id'])
 
+        if CONF.identity_feature_enabled.forbid_global_implied_dsr:
+            # The contrary is not true: we can't create an inference rule
+            # from a global role to a domain role
+            self.assertRaises(
+                lib_exc.Forbidden,
+                self.roles_client.create_role_inference_rule,
+                self.role['id'],
+                domain_role1['id'])
+
     @decorators.idempotent_id('3859df7e-5b78-4e4d-b10e-214c8953842a')
     def test_assignments_for_domain_roles(self):
         domain_role = self.setup_test_role(domain_id=self.domain['id'])
diff --git a/tempest/cmd/run.py b/tempest/cmd/run.py
index 54b844a..b36bf5c 100644
--- a/tempest/cmd/run.py
+++ b/tempest/cmd/run.py
@@ -78,11 +78,20 @@
 subunit-trace output filter. But, if you would prefer a subunit v2 stream be
 output to STDOUT use the **--subunit** flag
 
+Combining Runs
+==============
+
+There are certain situations in which you want to split a single run of tempest
+across 2 executions of tempest run. (for example to run part of the tests
+serially and others in parallel) To accomplish this but still treat the results
+as a single run you can leverage the **--combine** option which will append
+the current run's results with the previous runs.
 """
 
 import io
 import os
 import sys
+import tempfile
 import threading
 
 from cliff import command
@@ -165,6 +174,12 @@
         else:
             print("No .testr.conf file was found for local execution")
             sys.exit(2)
+        if parsed_args.combine:
+            temp_stream = tempfile.NamedTemporaryFile()
+            return_code = run_argv(['tempest', 'last', '--subunit'], sys.stdin,
+                                   temp_stream, sys.stderr)
+            if return_code > 0:
+                sys.exit(return_code)
 
         regex = self._build_regex(parsed_args)
         if parsed_args.list_tests:
@@ -173,6 +188,16 @@
         else:
             options = self._build_options(parsed_args)
             returncode = self._run(regex, options)
+            if returncode > 0:
+                sys.exit(returncode)
+
+        if parsed_args.combine:
+            return_code = run_argv(['tempest', 'last', '--subunit'], sys.stdin,
+                                   temp_stream, sys.stderr)
+            if return_code > 0:
+                sys.exit(return_code)
+            returncode = run_argv(['tempest', 'load', temp_stream.name],
+                                  sys.stdin, sys.stdout, sys.stderr)
         sys.exit(returncode)
 
     def get_description(self):
@@ -231,6 +256,10 @@
         # output args
         parser.add_argument("--subunit", action='store_true',
                             help='Enable subunit v2 output')
+        parser.add_argument("--combine", action='store_true',
+                            help='Combine the output of this run with the '
+                                 "previous run's as a combined stream in the "
+                                 "testr repository after it finish")
 
         parser.set_defaults(parallel=True)
         return parser
diff --git a/tempest/config.py b/tempest/config.py
index 83c5c0e..651c32e 100644
--- a/tempest/config.py
+++ b/tempest/config.py
@@ -225,6 +225,13 @@
                 deprecated_for_removal=True,
                 deprecated_reason="All supported version of OpenStack now "
                                   "supports the 'reseller' feature"),
+    # TODO(rodrigods): This is a feature flag for bug 1590578 which is fixed
+    # in Newton and Ocata. This option can be removed after Mitaka is end of
+    # life.
+    cfg.BoolOpt('forbid_global_implied_dsr',
+                default=False,
+                help='Does the environment forbid global roles implying '
+                     'domain specific ones?'),
     cfg.BoolOpt('security_compliance',
                 default=False,
                 help='Does the environment have the security compliance '