NEXUS-5218 this was done - however I could find no record of the actual commit, by searching git history and grepping source code it. Connecting to nexus 2.4.0-08 with visual vm does not show the property being set either.
In the case of running with Java 7 and inside a network with a router that does not understand IPv6, this could present an issue.
You may also run into issues connecting to the JMX interface (even locally) because by default JMX binds to IPv6 if it's available. This case is also solved by passing '-Djava.net.preferIPv4Stack=true' explicitly as a JVM option. This will prompt JMX to bind to a given IPv4 IP address.