title: Re-download a SNAPSHOT version of a dependency using SBT
body: <p>I have the following lines in my <code>build.sbt</code> file.</p>
  
  <pre><code>resolvers += "specs2 snapshot repo" at "http://scala-tools.org/repo-snapshots"
  
  libraryDependencies += "org.specs2" %% "specs2" % "1.7-SNAPSHOT" % "test"
  </code></pre>
  
  <p>Now if the snapshot has changed (is this reasonable at all, that a maven SNAPSHOT version changes without its version number changing?), how can I tell sbt to download the new version? Using <code>update</code> does nothing.</p>