title: Error while merging dex archives
body: <p>I am building a small Android app with Kotlin and Android Studio. Everything worked fine, but out of the blue (at least what seems to me), I am stuck  with</p>
  
  <pre><code>Error:Execution failed for task :bahndb:transformDexArchiveWithExternalLibsDexMergerForDebugAndroidTest'.
  &gt; com.android.builder.dexing.DexArchiveMergerException: 
  Error while merging dex archives: 
  C:\Users\Dieter\AndroidStudioProjects\zuegliwidget\bahndb\build\intermediates\transforms\dexBuilder\androidTest\debug\13.jar,
  </code></pre>
  
  <p>and so on until 47.jar when I try to run an Instrumented Test. Local tests all work ok. It is strange that even earlier checkout that had worked before show this behaviour (some update? I have reinstalled Android Studio twice)</p>
  
  <p>I have read all message on the subject here, none helped:</p>
  
  <ul>
  <li>Use clean build (I do every time)</li>
  <li>Invalidate cache (over and over)</li>
  <li>added multiDex</li>
  <li>Tried different Kotlin plugins</li>
  <li>Uninstalled 3.1 Canary 5, installed stable, reinstalled canary 5</li>
  <li>Un/commented dependencies one after the other (this had worked earlier)
  Running Lint, but failed with error</li>
  </ul>
  
  <p>App has 2 submodules, bahndb and http. Here are the gradle files, if it matters</p>
  
  <p><a href="https://github.com/dmenne/zuegliwidget/blob/master/build.gradle" rel="nofollow noreferrer">https://github.com/dmenne/zuegliwidget/blob/master/build.gradle</a></p>
  
  <p><a href="https://github.com/dmenne/zuegliwidget/blob/master/app/build.gradle" rel="nofollow noreferrer">https://github.com/dmenne/zuegliwidget/blob/master/app/build.gradle</a></p>
  
  <p><a href="https://github.com/dmenne/zuegliwidget/blob/master/bahndb/build.gradle" rel="nofollow noreferrer">https://github.com/dmenne/zuegliwidget/blob/master/bahndb/build.gradle</a> &lt;&lt; Most likely guilty</p>
  
  <p><a href="https://github.com/dmenne/zuegliwidget/blob/master/http/build.gradle" rel="nofollow noreferrer">https://github.com/dmenne/zuegliwidget/blob/master/http/build.gradle</a></p>
  
  <p>Is there a systematic approach to locate the source of the problem</p>