title: Maven release plugin fails : source artifacts getting deployed twice
body: <p>We are using the maven release plugin on hudson and trying to automate the release process.
  The release:prepare works fine. When we try to do the release:perform , it fails because it tries to upload a source artifact twice to the repository.</p>
  
  <p>Things that I tried,</p>
  
  <ol>
  <li>removing the profile which does include the maven source plugin from the super pom ( did not work)</li>
  <li>specifying the goals on hudson for release as -P!attach-source release:prepare release:perform. Which I thought will exclude the source plugin from getting executed. (did not work).</li>
  <li>tried specifying the plugin phase to some non existent phase in the super pom.(Did not work)</li>
  <li>tried specifying the plugin configuration, forReleaseProfile as false. ( guess what?? Did not work too)</li>
  </ol>
  
  <p>It still spits out this error.</p>
  
  <pre><code>[INFO] [DEBUG] Using Wagon implementation lightweight from default mapping for protocol http
  [INFO] [DEBUG] Using Wagon implementation lightweight from default mapping for protocol http
  [INFO] [DEBUG] Checking for pre-existing User-Agent configuration.
  [INFO] [DEBUG] Adding User-Agent configuration.
  [INFO] [DEBUG] not adding permissions to wagon connection
  [INFO] Uploading: http://xx.xx.xx.xx:8081/nexus/content/repositories/releases//com/yyy/xxx/hhh/hhh-hhh/1.9.40/hhh-hhh-1.9.40-sources.jar
  [INFO] 57K uploaded  (xxx-xxx-1.9.40-sources.jar)
  [INFO] [DEBUG] Using Wagon implementation lightweight from default mapping for protocol http
  [INFO] [DEBUG] Using Wagon implementation lightweight from default mapping for protocol http
  [INFO] [DEBUG] Checking for pre-existing User-Agent configuration.
  [INFO] [DEBUG] Adding User-Agent configuration.
  [INFO] [DEBUG] not adding permissions to wagon connection
  [INFO] Uploading: http://xx.xxx.xx.xx:8081/nexus/content/repositories/releases//com/xxx/xxxx/xxx/xxx-xxx/1.9.40/xxx-xxx-1.9.40-sources.jar
  [INFO] [DEBUG] Using Wagon implementation lightweight from default mapping for protocol http
  [INFO] [INFO] ------------------------------------------------------------------------
  [INFO] [ERROR] BUILD ERROR
  [INFO] [INFO] ------------------------------------------------------------------------
  [INFO] [INFO] Error deploying artifact: Authorization failed: Access denied to: http://xx.xxx.xx.xx:8081/nexus/content/repositories/releases/com/xxx/xxx/xxx/xxx-config/1.9.40/xxx-xxx-1.9.40-sources.jar
  </code></pre>
  
  <p>Any help regarding this will be really appreciated.</p>