title: Why does mappings in Universal have no effect on what's included in tarball?
body: <p>A summary of my <code>build.sbt</code> looks like this:</p>
  
  <pre><code>import com.github.bigtoast.sbtliquibase.LiquibasePlugin
  import S3._
  import com.typesafe.sbt.SbtNativePackager._
  import com.typesafe.sbt.SbtNativePackager.Universal
  import com.typesafe.sbt.packager.Keys._
  import Path.flat
  
  mappings in Universal ++= {
    ((baseDirectory.value / "src/main/migrations" * "*").get map { f =&gt; f -&gt; (f.name) })
  }
  </code></pre>
  
  <p>When I run <code>universal:packageZipTarball</code> I expect the files I have in <code>src/main/migrations</code> to appear in the final tarball. They don't.</p>
  
  <p>What I see is:</p>
  
  <pre><code>a database2-0.34.0
  a database2-0.34.0/lib
  a database2-0.34.0/lib/com.trailhunger.database2-0.34.0.jar
  a database2-0.34.0/lib/org.postgresql.postgresql-9.3-1101-jdbc4.jar
  a database2-0.34.0/lib/org.scala-lang.scala-library-2.10.3.jar
  </code></pre>
  
  <p>Very similar code in a another project in my build works perfectly.</p>