Because of the danger of Java deserialization when using RMI, we (PMC) have decided to comment out RMI related code.
We decided to comment out as less as possible because when, in the start and both properties, the rmi part is off and the RMI test services are off there is no RMI related danger left (RMI test services are not a danger but would fail during tests run).
It's then easier for users who need RMI in their projects to have only to uncomment those and not digg everywhere.
Note that since the naming (JNDI) server relies on the rmi loader it will also fail.
You can get more information in wiki page linked below in the "Issue Links" section.