title: Brew services start but postgresql94 does not
body: <h2>Current situation:</h2>
  <p>I'm trying to install and run <code>postgresql 9.4</code> via <code>homebrew</code>.</p>
  <p>It installs fine, and when I run <code>brew services start postgresql94</code>, it says it started correctly.</p>
  <p>However there is no <code>postgres</code> process running in <code>ps</code> and <code>psql</code> can't connect.</p>
  <p>I can start it with <code>postgres -D</code>, but trying to log in via <code>psql -U postgres</code> tells me that the <code>postgres</code> role doesn't exist and I can't figure out another default to using. (my local user also doesn't exist as a role)</p>
  <h2>How I got here:</h2>
  <p>I'm trying to set up a new dev environment with an existing <code>Rails 4.1.8</code> app.</p>
  <p>I originally installed <code>postgresql 9.5</code> via <code>homebrew</code> which worked happily until I attempted to migrate which failed with <a href="https://github.com/rails/rails/issues/23039" rel="nofollow noreferrer">this error</a>.</p>
  <p>I cannot upgrade to a newer version of <code>Rails</code>.  I've searched around a bunch and I'm surprised more people haven't run into this problem.</p>
  <p>If you have any suggestions to either of the above I would really appreciate it.</p>