title: org.codehaus.mojo:cobertura-maven-plugin does not exist or no valid version
body: <p>The pom build file works fine before, but today, I am seeing error of
  Caused by: org.apache.maven.plugin.version.PluginVersionNotFoundException: The plugin 'org.codehaus.mojo:cobertura-maven-plugin' does not exist or no valid version could be found</p>
  
  <p>I run mvn with "-X", and I am not seeing it tried to resolve or load from remote repository.</p>
  
  <p>[DEBUG] cobertura-maven-plugin: using locally installed snapshot
  [DEBUG] Artifact not found - using stub model: Unable to determine the latest version</p>
  
  <p>To force it reload repository, I removed org\codehaus folder from my local repository, still got the same error. </p>
  
  <p>I am very curious to know why maven does not load it from external repository. Here is the stack trace.</p>
  
  <pre><code>Caused by: org.apache.maven.plugin.version.PluginVersionNotFoundException: The plugin 'org.codehaus.mojo:cobertura-maven-plugin' does not exist or no valid version could be found
      at org.apache.maven.plugin.version.DefaultPluginVersionManager.resolvePluginVersion(DefaultPluginVersionManager.java:229)
      at org.apache.maven.plugin.version.DefaultPluginVersionManager.resolvePluginVersion(DefaultPluginVersionManager.java:91)
      at org.apache.maven.plugin.DefaultPluginManager.verifyPlugin(DefaultPluginManager.java:179)
      at org.apache.maven.plugin.DefaultPluginManager.loadPluginDescriptor(DefaultPluginManager.java:1642)
      at org.apache.maven.lifecycle.DefaultLifecycleExecutor.verifyPlugin(DefaultLifecycleExecutor.java:1540)
  </code></pre>