Switch tempest verify-config usage to avoid bug

This commit will unblock the world breakage caused by the recent
cliff release. This exposes a hole in our constraints usage in
devstack. We need to fix this bug for real in devstack and cliff,
but that will take a few minutes to an hour or so. So let's just
change the usage in the meantime, we can revert this when things
are fixed for real.

Related-Bug: #1543841

Depends-On: Ic63612dc50e064a3a69b88618e394ba17e083c22
Change-Id: I19e477fa5068474bc3471307732f89adaafb2952
diff --git a/lib/tempest b/lib/tempest
index add1b0e..e90ff93 100644
--- a/lib/tempest
+++ b/lib/tempest
@@ -321,7 +321,7 @@
     local tmp_cfg_file
     tmp_cfg_file=$(mktemp)
     cd $TEMPEST_DIR
-    tox -revenv -- tempest verify-config -uro $tmp_cfg_file
+    tox -revenv -- tempest verify-config -u -r -o $tmp_cfg_file
 
     local compute_api_extensions=${COMPUTE_API_EXTENSIONS:-"all"}
     if [[ ! -z "$DISABLE_COMPUTE_API_EXTENSIONS" ]]; then