title: Android Studio 3.1: mixing versions can lead to runtime crashes
body: <p>Have recently upgraded to Android Studio 3.1, and at the same time I'm trying the Android P preview.</p>
  
  <p>I'm getting the following error on compiling:</p>
  
  <blockquote>
    <p>All com.android.support libraries must use the exact same version specification (mixing versions can lead to runtime crashes). Found versions 28.0.0-alpha1, 26.1.0. Examples include com.android.support:animated-vector-drawable:28.0.0-alpha1 and com.android.support:support-media-compat:26.1.0 less... (Ctrl+F1) 
    There are some combinations of libraries, or tools and libraries, that are incompatible, or can lead to bugs. One such incompatibility is compiling with a version of the Android support libraries that is not the latest version (or in particular, a version lower than your targetSdkVersion).</p>
  </blockquote>
  
  <p>But I cannot see any instance of <code>26.1.0</code> anywhere.  All I have in my gradle is:</p>
  
  <pre><code>implementation 'com.android.support:appcompat-v7:28.0.0-alpha1'
  implementation 'com.android.support:design:28.0.0-alpha1'
  </code></pre>
  
  <p>I've tried clearing caches, rebuilding app, etc.  But error remains.</p>