title: Capistrano fails when trying to deploy Rails asset manifest
body: <p>I'm trying to deploy a Rails app that has worked successfully before, but Capistrano is barfing during deployment. I don't believe I've changed anything other than changing the Rails app code itself and updating some gems (i.e. the deploy.rb file is identical to a once-working setup.)</p>
  
  <p>Here's the line it appears to fail on:</p>
  
  <pre><code>executing "cp -- /u/apps/myapp/shared/assets/manifest.yml /u/apps/myapp/releases/unable/assets_manifest.yml"
  </code></pre>
  
  <p>Notice how the directory it's trying to copy to is called <code>unable</code>. It's like it can't get the new release name/date or something? And yet earlier it executes this without error:</p>
  
  <pre><code>executing "cd -- /u/apps/myapp/releases/20130507041223 &amp;&amp; bundle exec rake RAILS_ENV=production RAILS_GROUPS=assets assets:precompile"
  </code></pre>
  
  <p>The remainder of the interesting output is this:</p>
  
  <pre><code>** cp: cannot create regular file `/u/apps/myapp/releases/unable/assets_manifest.yml'
  ** No such file or directory
  failed: "rvm_path=$HOME/.rvm/ $HOME/.rvm/bin/rvm-shell 'default' -c 'cp -- /u/apps/myapp/shared/assets/manifest.yml /u/apps/myapp/releases/unable/assets_manifest.yml'"
  </code></pre>
  
  <p><strong>UPDATE:</strong> This appears to be a bug in Capistrano 2.15.4. Downgrading to version 2.14.2 fixed the problem. I've detailed the bug here:</p>
  
  <p><a href="https://github.com/capistrano/capistrano/issues/468">https://github.com/capistrano/capistrano/issues/468</a></p>