title: Maven site-deploy build error
body: <p>When I run "mvn install site-deploy" lately in the build I get the following error continuously. I cannot figure out what's wrong as I've
  replaced the m2 repo also tried several clean builds. Could somebody give me a hint where I can find a solution. I tried googling but could not
  come across something relevant. Thanks.</p>
  
  <pre><code> FATAL ERROR] org.apache.maven.plugins.site.SiteMojo#execute() caused a linkage error (java.lang.NoClassDefFoundError) and may be out-of-date. Check the realms:
  [FATAL ERROR] Plugin realm = app0.child-container[org.apache.maven.plugins:maven-site-plugin:2.0-beta-7]
  ......
  [FATAL ERROR] Container realm = plexus.core
  .......
  [INFO] ------------------------------------------------------------------------
  [ERROR] FATAL ERROR
  [INFO] ------------------------------------------------------------------------
  [INFO] org/apache/maven/plugin/logging/Log
  org.apache.maven.plugin.logging.Log
  [INFO] ------------------------------------------------------------------------
  [INFO] Trace
  java.lang.NoClassDefFoundError: org/apache/maven/plugin/logging/Log
      at org.codehaus.mojo.emma.EmmaReportMojo.canGenerateReport(EmmaReportMojo.java:319)
      at org.apache.maven.plugins.site.AbstractSiteRenderingMojo.filterReports(AbstractSiteRenderingMojo.java:177)
      at org.apache.maven.plugins.site.SiteMojo.execute(SiteMojo.java:81)
      at org.apache.maven.plugin.DefaultPluginManager.executeMojo(DefaultPluginManager.java:483)
      at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoals(DefaultLifecycleExecutor.java:678)
      at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalWithLifecycle(DefaultLifecycleExecutor.java:540)
      at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoal(DefaultLifecycleExecutor.java:519)
      at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalAndHandleFailures(DefaultLifecycleExecutor.java:371)
      at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeTaskSegments(DefaultLifecycleExecutor.java:332)
      at org.apache.maven.lifecycle.DefaultLifecycleExecutor.execute(DefaultLifecycleExecutor.java:181)
      at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:356)
      at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:137)
      at org.apache.maven.cli.MavenCli.main(MavenCli.java:356)
      at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
      at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
      at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
      at java.lang.reflect.Method.invoke(Method.java:597)
      at org.codehaus.classworlds.Launcher.launchEnhanced(Launcher.java:315)
      at org.codehaus.classworlds.Launcher.launch(Launcher.java:255)
      at org.codehaus.classworlds.Launcher.mainWithExitCode(Launcher.java:430)
      at org.codehaus.classworlds.Launcher.main(Launcher.java:375)
  Caused by: java.lang.ClassNotFoundException: org.apache.maven.plugin.logging.Log
      at java.net.URLClassLoader$1.run(URLClassLoader.java:200)
      at java.security.AccessController.doPrivileged(Native Method)
      at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
      at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
      at org.codehaus.classworlds.RealmClassLoader.loadClassDirect(RealmClassLoader.java:195)
      at org.codehaus.classworlds.DefaultClassRealm.loadClass(DefaultClassRealm.java:255)
      at org.codehaus.classworlds.RealmClassLoader.loadClass(RealmClassLoader.java:214)
      at java.lang.ClassLoader.loadClass(ClassLoader.java:252)
      at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320)
      ... 21 more
  </code></pre>
  
  <p>Version Information:
  jdk1.6.0_14,apache-maven-2.1.0</p>