Как изменить порт HTTP, который прослушивает Play2

В документации написано:

$play start

Примечание: порт HTTP можно установить, передав системную переменную -Dhttp.port

но я по-прежнему проигрываю ошибку 9000 портов.

$ /opt/play-2.0/play start -Dhttp.port=9001

[info] Loading project definition from /my/path
[info] Set current project to marmurka (in build file:/my/path/)

(Starting server. Type Ctrl+D to exit logs, the server will remain in background)

Play server process ID is 27505
[info] play - Application started (Prod)
Oops, cannot start the server.
org.jboss.netty.channel.ChannelException: Failed to bind to: /0.0.0.0:9000
    at org.jboss.netty.bootstrap.ServerBootstrap.bind(ServerBootstrap.java:298)
    at play.core.server.NettyServer.<init>(NettyServer.scala:63)
    at play.core.server.NettyServer$.createServer(NettyServer.scala:131)
    at play.core.server.NettyServer$$anonfun$main$5.apply(NettyServer.scala:153)
    at play.core.server.NettyServer$$anonfun$main$5.apply(NettyServer.scala:152)
    at scala.Option.map(Option.scala:133)
    at play.core.server.NettyServer$.main(NettyServer.scala:152)
    at play.core.server.NettyServer.main(NettyServer.scala)
Caused by: java.net.BindException: Address already in use
    at sun.nio.ch.Net.bind(Native Method)
    at sun.nio.ch.ServerSocketChannelImpl.bind(ServerSocketChannelImpl.java:137)
    at sun.nio.ch.ServerSocketAdaptor.bind(ServerSocketAdaptor.java:77)
    at org.jboss.netty.channel.socket.nio.NioServerSocketPipelineSink.bind(NioServerSocketPipelineSink.java:140)
    at     org.jboss.netty.channel.socket.nio.NioServerSocketPipelineSink.handleServerSocket(NioServerSocketPipelineSink.java:92)
    at org.jboss.netty.channel.socket.nio.NioServerSocketPipelineSink.eventSunk(NioServerSocketPipelineSink.java:66)
    at org.jboss.netty.channel.Channels.bind(Channels.java:462)
    at org.jboss.netty.channel.AbstractChannel.bind(AbstractChannel.java:186)
    at org.jboss.netty.bootstrap.ServerBootstrap$Binder.channelOpen(ServerBootstrap.java:343)
    at org.jboss.netty.channel.Channels.fireChannelOpen(Channels.java:170)
    at org.jboss.netty.channel.socket.nio.NioServerSocketChannel.<init>(NioServerSocketChannel.java:77)
    at org.jboss.netty.channel.socket.nio.NioServerSocketChannelFactory.newChannel(NioServerSocketChannelFactory.java:137)
    at org.jboss.netty.channel.socket.nio.NioServerSocketChannelFactory.newChannel(NioServerSocketChannelFactory.java:85)
    at org.jboss.netty.bootstrap.ServerBootstrap.bind(ServerBootstrap.java:277)
    ... 7 more