Steps to reproduce the problem:
1.Create an APK which also has an assets directory which is imported in the form:
android_assets("some_assets") {
  sources = [
    "some/dir/",
  ]
}

2. Build once.
3. Change the contents of some/dir/.
4. Build again.

What is the expected behavior?
I would expect the build procedure to notice that the directory's contents have changed, and the APK to be updated.

What went wrong?
The APK is not updated. To trigger an update, I need to comment out "some/dir/", build, then uncomment and build again.

Did this work before? N/A 

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