title: cabal-install does not retain the version for happy
body: <p>I've trying to do <code>cabal install hoogle</code> but there is a hickup with the <code>haskell-src-exts-1.13.5</code> dependency:</p>
  
  <pre><code>Configuring haskell-src-exts-1.13.5...
  setup: The program happy version &gt;=1.17 is required but it could not be found.
  </code></pre>
  
  <p>When I try to do <code>cabal install happy</code> it seems to finish successfully, but cabal-install does not retain the version:</p>
  
  <pre><code>&gt;$ cabal list happy
  * happy
      Synopsis: Happy is a parser generator for Haskell
      Default available version: 1.18.10
      Installed versions: [ Unknown ]
      Homepage: http://www.haskell.org/happy/
      License:  BSD3
  </code></pre>
  
  <p>As you can see the version is <code>[ Unknown ]</code>. It stays unknown, and cabal-install remains oblivious if I try to run <code>cabal install happy</code> again.</p>
  
  <p>What gives?</p>
  
  <p>Thanks in advance!</p>