title: assembleRelease fails with react-native 0.50
body: <p>Using gradle-plugin 3.0.0
  Gradle distribution 4.1.0
  react-native 0.50
  Linux fedora 27</p>
  
  <p>app name is u1b.
  Project structure
  /proj/mob/rn.common    (this is where node_modules is and all my js related stuff)
  /proj/mob/a/u1b   -- is where the android app is.</p>
  
  <p>the project structure is different than the one normally created by boiler plate react-native create app script (because my node_modules is not just one level up from the android app).
  But not clear if this is an issue or not.</p>
  
  <p>I have been building my android with react-native library, in debug mode.
  Now its time to start building release.
  But I am running into a problem</p>
  
  <p>bash gradlew assembleRelease errors out :</p>
  
  <pre><code>&gt; Task :app:bundleReleaseJsAndAssets
  Scanning folders for symlinks in /home/v/devel/mine/proj/mob/rn.common/node_modules (12ms)
  Scanning folders for symlinks in /home/v/devel/mine/proj/mob/rn.common/node_modules (9ms)
  Loading dependency graph, done.
  warning: the transform cache was reset.
  bundle: start
  bundle: finish
  bundle: Writing bundle output to: /home/v/tmp/u1b/app/intermediates/assets/release/index.android.bundle
  bundle: Done writing bundle output
  bundle: Copying 18 asset files
  bundle: Done copying assets
  
  /home/v/tmp/u1b/app/intermediates/res/merged/release/drawable-mdpi/src_jsapp_img_material_ic_local_library_black_48dp_android_drawablexxhlack_48dp.png: **error: Invalid filename.  Unable to add.**
  </code></pre>
  
  <p>The image file it is looking at is, indeed not there. However I have no idea how that file name is constructed and, why it something is looking for it.</p>
  
  <p>my gradle.properties contains a flag to switch to old apk due to a bug</p>
  
  <pre><code># https://github.com/react-community/react-navigation/issues/1976
  android.enableAapt2=false
  </code></pre>
  
  <p>could somebody shed a light on how the image names are decided and what might be causing the error</p>
  
  <p>thank you</p>