title: fish shell prompt not showing symbols correctly
body: <p>I've installed fish, and the agnoster theme througth oh-my-fish;
  Now I have the prompt not showing correctly symbols;</p>
  
  <p><a href="https://i.stack.imgur.com/qJ84a.jpg" rel="noreferrer"><img src="https://i.stack.imgur.com/qJ84a.jpg" alt="my fish prompt"></a></p>
  
  <p>Can someone explain what's wrong?</p>