Problems using Maven to initialize a local thoughtsite (App Engine sample) project in Eclipse

This sample app ("thoughtsite") for App Engine contains a pom.xml in its trunk:

http://code.google.com/p/thoughtsite/source/browse/#svn/trunk

I ran mvn eclipse:eclipse and also tried using m2eclipse to import this source code into an Eclipse project.

But I end up with this error despite the fact that I have the Google App Engine plugin and the Google App Engine SDK installed:

Exception in thread "main" java.lang.ExceptionInInitializerError
    at com.google.appengine.tools.info.SdkImplInfo.<clinit>(SdkImplInfo.java:19)
    at com.google.appengine.tools.util.Logging.initializeLogging(Logging.java:36)
    at com.google.appengine.tools.development.DevAppServerMain.main(DevAppServerMain.java:82)
Caused by: java.lang.RuntimeException: Unable to discover the Google App Engine SDK root. This code should be loaded from the SDK directory, but was instead loaded from file:~/.m2/repository/com/google/appengine/appengine-tools-sdk/1.3.0/appengine-tools-sdk-1.3.0.jar.  Specify -Dappengine.sdk.root to override the SDK location.
    at com.google.appengine.tools.info.SdkInfo.findSdkRoot(SdkInfo.java:106)
    at com.google.appengine.tools.info.SdkInfo.<clinit>(SdkInfo.java:24)
    ... 3 more

When I go into the project settings under "Google" and try to set it to use the default App Engine SDK it always reverts to trying to use Maven开发者_运维问答's App Engine SDK instead. No idea how to get this project working.