Upgrade httpclient to 4.1 in HttpBuilder

We are running into some major issues with the older dependency of httpclient 4.0 in some grails plugins. It is currently preventing us from using the release plugin (the de-facto way of publishing projects, which we need) and geb (functional testing, which we would very much like to use) together. Is there any possibility of upgrading httpclient/httpcore to 4.1 or the latest version?

See this question also: http://groovy.329449.n5.nabble.com/Is-it-possible-to-update-the-org-apache-httpcomponents-dependencies-used-by-http-builder-td4990723.html

And this thread on the grails user mailing list: http://grails.1312388.n4.nabble.com/Geb-Grails-tests-only-work-on-first-execution-td3675543.html#a4040087