title: ZSH setopt PROMPT_SUBST not working
body: <p>I'm trying to get customize my zsh prompt and want to evaluation a function with git commands every time my prompt is generated. I'm using <code>setopt PROMPT_SUBST</code>, but it doesn't seem to be working. This is my zshrc:</p>
  
  <pre><code>setopt PROMPT_SUBST
  autoload -U colors &amp;&amp; colors # Enable colors
  
  # Show Git branch/tag, or name-rev if on detached head
  parse_git_branch() {
    echo "PARSING GIT BRANCH"
    (git symbolic-ref -q HEAD || git name-rev --name-only --no-undefined --always HEAD) 2&gt; /dev/null
  }
  
  prompt() {
      echo -n "%/"
      echo "$(git status)"
  }
  
  PS1="$(prompt)"
  </code></pre>
  
  <p>And this is my output of <code>setopt</code>:</p>
  
  <pre><code>interactive
  login
  monitor
  nonomatch
  promptsubst
  shinstdin
  zle
  </code></pre>