title: Android flavors, Gradle sourceSets merging
body: <p>I try to make an application for multiple partners and for each partner a test and prod version. For each flavors I create a specific folder with res/values in it like the documentation said.</p>
  
  <p>My gradle file look like this : </p>
  
  <pre><code>apply plugin: 'com.android.application'
  
  android {
      packagingOptions {
          exclude 'META-INF/LICENSE'
          exclude 'META-INF/NOTICE'
      }
      compileSdkVersion 14
      buildToolsVersion "21.1.2"
  
      defaultConfig {
              versionCode 1
              versionName 1
              minSdkVersion 14
              targetSdkVersion 19
          }
  
      productFlavors {
          prodPARTNER1 {
              applicationId "com.PARTNER1"
          }
  
          testPARTNER1 {
              applicationId "com.PARTNER1.test"
          }
          prodPARTNER2{
              applicationId "com.PARTNER2"
          }
  
          testPARTNER2{
              applicationId "com.PARTNER2.test"
          }
      }
      sourceSets {
          testPARTNER2 {
              res.srcDirs = ["testPARTNER2/res", "prodPARTNER2/res"]
          }
      }
  
  }
  
  dependencies {
      compile project(':ViewPagerIndicatorLibrary')
      compile 'com.android.support:support-v4:19.0.0'
      compile 'com.google.android.gms:play-services:+'
      compile files('libs/achartengine-1.1.0.jar')
      compile files('libs/android-async-http-1.4.4.jar')
      compile files('libs/jackson-annotations-2.2.3.jar')
      compile files('libs/jackson-core-2.2.3.jar')
      compile files('libs/jackson-databind-2.2.3.jar')
      compile files('libs/urlimageviewhelper-1.0.4.jar')
  }
  </code></pre>
  
  <p>I want for a test version to take res folder of the prod version (like this I not duplicate resources for both version) and merge it with the test version.
  The problem is :</p>
  
  <p><code>Error:Error: Duplicate resources:</code> 
  <code>C:\...prodPARTNER2\res\values\strings.xml:string/app_name,</code>         <code>C:\...testPARTNER2\res\values\strings.xml:string/app_name</code></p>
  
  <p>Any idea ? It's not possible to merge too res folder for the same flavors ?</p>
  
  <p>EDIT : I use gradle v 1.1.0 and android studio v 1.1.0 too</p>