SOLR-554 for the original improvement.
This has a bug in it. If I submit the form using multicore, it goes to /solr/admin/logging (not the right path).
I'm guessing this is because of the path trickery in SolrDispathFilter but I can't follow what the best procedure is to fix it.
The simplest thing to do is to not use request.getRequestURI() because a form with no action submits to itself.