TEMPEST_PY26_NOSE_COMPAT in py26 jobs

Use py26 skip exception compatibility code path in py26 jobs.

Change-Id: Id6c29f26f19f69abab558d5f94d8cbf6190ed43b
diff --git a/run_tests.sh b/run_tests.sh
index acd9497..970da51 100755
--- a/run_tests.sh
+++ b/run_tests.sh
@@ -107,12 +107,13 @@
 }
 
 function run_tests_nose {
-    NOSE_WITH_OPENSTACK=1
-    NOSE_OPENSTACK_COLOR=1
-    NOSE_OPENSTACK_RED=15.00
-    NOSE_OPENSTACK_YELLOW=3.00
-    NOSE_OPENSTACK_SHOW_ELAPSED=1
-    NOSE_OPENSTACK_STDOUT=1
+    export NOSE_WITH_OPENSTACK=1
+    export NOSE_OPENSTACK_COLOR=1
+    export NOSE_OPENSTACK_RED=15.00
+    export NOSE_OPENSTACK_YELLOW=3.00
+    export NOSE_OPENSTACK_SHOW_ELAPSED=1
+    export NOSE_OPENSTACK_STDOUT=1
+    export TEMPEST_PY26_NOSE_COMPAT=1
     if [[ "x$noseargs" =~ "tempest" ]]; then
         noseargs="$testrargs"
     else