The subversion installed on the default elastic bamboo AMI uses its own bundled ssl library. This library doesn't know where to look for the root CA certificates (/etc/pki/tls/certs/ca-bundle.crt), and so consequently no matter what URL you hit, if it's https, the SVN client will throw an error saying that it doesn't trust it.

I'm not sure where the build of SVN came from that is installed on the agents, if we compiled it ourselves then the solution is to point SVN at the fedoras OpenSSL installation. If not, then we need to compile our own, as it's pretty stupid having an SVN install that doesn't support SSL.