Just some food for thought... You might consider adopting a "Developer
Certificate of Origin" (with agreement indicated by a Signed-off-by
footer in git commit messages) like the Linux kernel, rather than a CLA.
A good summary here:
http://lwn.net/Articles/592503/
The wording of the Linux DCO doesn't give permission to re-license but
if new code is contributed under GPLv2+ it seems like that should give
you enough leeway to deal with the GPLv3-only stuff.
It also has the advantage of avoiding the dread "CLA" phrase which in
many people's minds conjures up unpleasant images of copyright
assignment and proprietary re-licensing.
--
Dan Callaghan <dcallagh(a)redhat.com>
Software Engineer, Hosted & Shared Services
Red Hat, Inc.