title: Why is the error "Not a valid command: assembly-merge-strategy"?
body: <p>I have the following <code>build.sbt</code> file.</p>
  
  <pre><code>import AssemblyKeys._
  
  name := "approxstrmatch"
  
  version := "1.0"
  
  scalaVersion := "2.10.4"
  
  libraryDependencies+="org.apache.spark" %% "spark-core" % "1.0.0"
  
  resolvers += "AkkaRepository" at "http://repo.akka.io/releases/"
  
  // My merge strategy is specified here.
  
  lazy val app = Project("approxstrmatch", file("approxstrmatch"),
      settings = buildSettings ++ assemblySettings ++ Seq(
      mergeStrategy in assembly &lt;&lt;= (mergeStrategy in assembly) { (old) =&gt;
      {
          case PathList("javax", "servlet", xs @ _*)         =&gt; MergeStrategy.first
          case PathList("javax", "transaction", xs @ _*)     =&gt; MergeStrategy.first
          case PathList("javax", "mail", xs @ _*)     =&gt; MergeStrategy.first
          case PathList("javax", "activation", xs @ _*)     =&gt; MergeStrategy.first
          case PathList(ps @ _*) if ps.last endsWith ".html" =&gt; MergeStrategy.first
          case "application.conf" =&gt; MergeStrategy.concat
          case "unwanted.txt"     =&gt; MergeStrategy.discard
          case x =&gt; old(x)
          }
      })
    )
  
  mainClass in assembly := Some("approxstrmatch.JaccardScore")
  // jarName in assembly := "approstrmatch.jar"
  </code></pre>
  
  <p>When I execute the following command <code>sbt assembly-merge-strategy</code> there's an error I don't understand. Any help appreciated.</p>
  
  <pre><code>approxstrmatch]$ sbt assembly-merge-strategy
  [info] Loading project definition from /apps/sameert/software/approxstrmatch/project
  [info] Set current project to approxstrmatch (in buildfile:/apps/sameert/software/approxstrmatch/)
  [error] Not a valid command: assembly-merge-strategy
  [error] No such setting/task
  </code></pre>