Description of problem:
Given router enable namespace labels, eg. NAMESPACE_LABELS=team=red. 
After that added the label(team=red) to namespace z1, then the router will be reloaded and the routes of z1 can work well by the router. But when updated or deleted the label of z1.  The router will NOT be reloaded. this cause the routes of z1 still can be works by the router.

Version-Release number of selected component (if applicable):


How reproducible:


Steps to Reproduce:
1. enable the router with NAMESPACE_LABELS=team=red
   oc set env dc router NAMESPACE_LABELS=team=red
2. Create namespaces z1 and test pod/svc/route
   oc create -f https://raw.githubusercontent.com/openshift-qe/v3-testfiles/master/routing/prometheus/service_pod.json -n z1
    oc expose svc hello-pod -n z1
3. Added the label for namespace z1 using admin user
   oc label namespace z1 team=red
4. Check the router logs
5. Check the route can be worked
6. Delete the label or update the label
   oc label namespace z1 team=blue --overwrite
7. Check the route again
8. Check the router logs

Actual results:
step 4. there will have logs shown "Router reloaded:" according to the time
step 6. the route still can be accessed
step 7. the route still can be accessed
step 8. NO new logs "Router reloaded:" shown

Expected results:

step 7. the route should NOT be accessed

Additional info: