Remove ZUUL_OLDREV and ZUUL_NEWREV

Removing old ZUUL_ env variables which have been replaced with
Ansible variables.

Change-Id: I5ed54b3c28c5b88a0262f102205f7c6dfa8be54a
diff --git a/tests/unit/test_github_driver.py b/tests/unit/test_github_driver.py
index 8493570..88408fa 100644
--- a/tests/unit/test_github_driver.py
+++ b/tests/unit/test_github_driver.py
@@ -115,8 +115,8 @@
         build_params = self.builds[0].parameters
         self.assertEqual('refs/tags/newtag', build_params['ZUUL_REF'])
         self.assertEqual('00000000000000000000000000000000',
-                         build_params['ZUUL_OLDREV'])
-        self.assertEqual(sha, build_params['ZUUL_NEWREV'])
+                         build_params['zuul']['oldrev'])
+        self.assertEqual(sha, build_params['zuul']['newrev'])
 
         self.executor_server.hold_jobs_in_build = False
         self.executor_server.release()
@@ -138,8 +138,8 @@
 
         build_params = self.builds[0].parameters
         self.assertEqual('refs/heads/master', build_params['ZUUL_REF'])
-        self.assertEqual(old_sha, build_params['ZUUL_OLDREV'])
-        self.assertEqual(new_sha, build_params['ZUUL_NEWREV'])
+        self.assertEqual(old_sha, build_params['zuul']['oldrev'])
+        self.assertEqual(new_sha, build_params['zuul']['newrev'])
 
         self.executor_server.hold_jobs_in_build = False
         self.executor_server.release()
diff --git a/zuul/executor/client.py b/zuul/executor/client.py
index 76dc8b7..6bf8084 100644
--- a/zuul/executor/client.py
+++ b/zuul/executor/client.py
@@ -215,9 +215,6 @@
             params['ZUUL_CHANGE'] = str(item.change.number)
             params['ZUUL_PATCHSET'] = str(item.change.patchset)
         if hasattr(item.change, 'ref') and item.change.ref is not None:
-            params['ZUUL_OLDREV'] = item.change.oldrev
-            params['ZUUL_NEWREV'] = item.change.newrev
-
             params['ZUUL_REF'] = item.change.ref
             params['ZUUL_COMMIT'] = item.change.newrev