If one calls fundrawtransaction, the change address will be retrieved from the keypool, though, this key/address will always be returned to the pool, leading to the problem that the next getnewaddress() call will restult in the same key/address.
Either we remove the auto-change-address (users would need to call getrawchangeaddress first [current best practice anyway]) or we add a call to keep/mark a specific key/address as change (after one have sent the funded raw transaction).
Reported by @NicolasDorier on IRC.