Attempting to Check Out a Newly Versionable Node Fails

If one adds mix:versionable as a mixin type to a node and then attempts to checkout before saving the node, a NullPointerException is thrown. This exception is thrown because the checkout operation attempts to access the base version for the node, but the base version (as well as the rest of the version graph for the node) does not get created until the node is saved.

According to section 8.2.6 of the JCR 1.0.1 spec, this should return silently. JR implements this correctly, causing a compatibility problem for us.