add TENANT_ARG to swift command line.

Fix bug 1020985.

Change-Id: I51733d37a50159a4b4872d61fa768d5bba3d6a03
diff --git a/exercises/client-args.sh b/exercises/client-args.sh
index 1d7d5b6..5e8d6f7 100755
--- a/exercises/client-args.sh
+++ b/exercises/client-args.sh
@@ -113,7 +113,7 @@
         STATUS_SWIFT="Skipped"
     else
         echo -e "\nTest Swift"
-        if swift $ARGS stat; then
+        if swift $TENANT_ARG $ARGS stat; then
             STATUS_SWIFT="Succeeded"
         else
             STATUS_SWIFT="Failed"