Cannot start both neo4j development and neo4j test servers

I have a Rails application backed by a Neo4j database. I've installed both a development server and a test server, as explained here and here. Each server works fine when started up alone, but if I try to start both, the second encounters a PortBindException. (Yes, I have configured the two servers to use different ports.)

How can I fix this problem so that I can start up both the development and test servers?

$ rake neo4j:start[development] ---> Successfully starts Neo4j development server
$ rake neo4j:start[test] ---> Fails to start Neo4j test server

Log file ([app_home_dir]/db/neo4j/test/logs/neo4j.log):

2016-05-27 06:45:05.346+0000 INFO  Starting...
2016-05-27 06:45:06.829+0000 INFO  Bolt enabled on localhost:7687.
2016-05-27 06:45:08.189+0000 ERROR Failed to start Neo4j: Starting Neo4j failed: Component 'org.neo4j.server.database.LifecycleManagingDatabase@9d02281' was successfully initialized, but failed to start. Please see attached cause exception. Starting Neo4j failed: Component 'org.neo4j.server.database.LifecycleManagingDatabase@9d02281' was successfully initialized, but failed to start. Please see attached cause exception.
org.neo4j.server.ServerStartupException: Starting Neo4j failed: Component 'org.neo4j.server.database.LifecycleManagingDatabase@9d02281' was successfully initialized, but failed to start. Please see attached cause exception.
    at org.neo4j.server.exception.ServerStartupErrors.translateToServerStartupError(ServerStartupErrors.java:68)
    at org.neo4j.server.AbstractNeoServer.start(AbstractNeoServer.java:217)
    at org.neo4j.server.ServerBootstrapper.start(ServerBootstrapper.java:81)
    at org.neo4j.server.ServerBootstrapper.start(ServerBootstrapper.java:60)
    at org.neo4j.server.CommunityEntryPoint.main(CommunityEntryPoint.java:28)
Caused by: org.neo4j.kernel.lifecycle.LifecycleException: Component 'org.neo4j.server.database.LifecycleManagingDatabase@9d02281' was successfully initialized, but failed to start. Please see attached cause exception.
    at org.neo4j.kernel.lifecycle.LifeSupport$LifecycleInstance.start(LifeSupport.java:444)
    at org.neo4j.kernel.lifecycle.LifeSupport.start(LifeSupport.java:107)
    at org.neo4j.server.AbstractNeoServer.start(AbstractNeoServer.java:189)
    ... 3 more
Caused by: java.lang.RuntimeException: Error starting org.neo4j.kernel.impl.factory.CommunityFacadeFactory, /Users/django09/Dropbox/Programming/projects/georgian_migration/db/neo4j/test/data/databases/graph.db
    at org.neo4j.kernel.impl.factory.GraphDatabaseFacadeFactory.newFacade(GraphDatabaseFacadeFactory.java:144)
    at org.neo4j.kernel.impl.factory.CommunityFacadeFactory.newFacade(CommunityFacadeFactory.java:40)
    at org.neo4j.kernel.impl.factory.GraphDatabaseFacadeFactory.newFacade(GraphDatabaseFacadeFactory.java:108)
    at org.neo4j.server.CommunityNeoServer.lambda$static$32(CommunityNeoServer.java:55)
    at org.neo4j.server.database.LifecycleManagingDatabase.start(LifecycleManagingDatabase.java:89)
    at org.neo4j.kernel.lifecycle.LifeSupport$LifecycleInstance.start(LifeSupport.java:434)
    ... 5 more
Caused by: org.neo4j.kernel.lifecycle.LifecycleException: Component 'org.neo4j.bolt.transport.NettyServer@59318c49' was successfully initialized, but failed to start. Please see attached cause exception.
    at org.neo4j.kernel.lifecycle.LifeSupport$LifecycleInstance.start(LifeSupport.java:444)
    at org.neo4j.kernel.lifecycle.LifeSupport.start(LifeSupport.java:107)
    at org.neo4j.kernel.lifecycle.LifeSupport$LifecycleInstance.start(LifeSupport.java:434)
    at org.neo4j.kernel.lifecycle.LifeSupport.start(LifeSupport.java:107)
    at org.neo4j.kernel.extension.KernelExtensions.start(KernelExtensions.java:86)
    at org.neo4j.kernel.lifecycle.LifeSupport$LifecycleInstance.start(LifeSupport.java:434)
    at org.neo4j.kernel.lifecycle.LifeSupport.start(LifeSupport.java:107)
    at org.neo4j.kernel.impl.factory.GraphDatabaseFacadeFactory.newFacade(GraphDatabaseFacadeFactory.java:140)
    ... 10 more
Caused by: org.neo4j.helpers.PortBindException: Address localhost:7687 is already in use, cannot bind to it.
    at sun.nio.ch.Net.bind0(Native Method)
    at sun.nio.ch.Net.bind(Net.java:433)
    at sun.nio.ch.Net.bind(Net.java:425)
    at sun.nio.ch.ServerSocketChannelImpl.bind(ServerSocketChannelImpl.java:223)
    at sun.nio.ch.ServerSocketAdaptor.bind(ServerSocketAdaptor.java:74)
    at io.netty.channel.socket.nio.NioServerSocketChannel.doBind(NioServerSocketChannel.java:125)
    at io.netty.channel.AbstractChannel$AbstractUnsafe.bind(AbstractChannel.java:485)
    at io.netty.channel.DefaultChannelPipeline$HeadContext.bind(DefaultChannelPipeline.java:1089)
    at io.netty.channel.AbstractChannelHandlerContext.invokeBind(AbstractChannelHandlerContext.java:430)
    at io.netty.channel.AbstractChannelHandlerContext.bind(AbstractChannelHandlerContext.java:415)
    at io.netty.channel.DefaultChannelPipeline.bind(DefaultChannelPipeline.java:903)
    at io.netty.channel.AbstractChannel.bind(AbstractChannel.java:198)
    at io.netty.bootstrap.AbstractBootstrap$2.run(AbstractBootstrap.java:348)
    at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:357)
    at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:357)
    at io.netty.util.concurrent.SingleThreadEventExecutor$2.run(SingleThreadEventExecutor.java:111)
    at java.lang.Thread.run(Thread.java:745)