Date in title shows as interval for no obvious reason

Question

I'm tweaking the titleFormat to get Friday, April 21, 2017 but I'm getting strange results:

• dddd renders Friday
• LL renders April 21, 2017
• But putting both together, dddd LL, renders as Friday, April 21, 2017 – April 21, 2017

What am I missing?

$(function() {
  $("#c1").fullCalendar({
    height: 100,
    defaultView: "agendaDay",
    allDaySlot: false,
    titleFormat: "dddd"
  });
  $("#c2").fullCalendar({
    height: 100,
    defaultView: "agendaDay",
    allDaySlot: false,
    titleFormat: "LL"
  });
  $("#c3").fullCalendar({
    height: 100,
    defaultView: "agendaDay",
    allDaySlot: false,
    titleFormat: "dddd LL"
  });
});

<link href='https://fullcalendar.io/js/fullcalendar-3.3.1/fullcalendar.css' rel='stylesheet' />
<link href='https://fullcalendar.io/js/fullcalendar-3.3.1/fullcalendar.print.css' rel='stylesheet' media='print' />
<script src='//cdnjs.cloudflare.com/ajax/libs/moment.js/2.9.0/moment.min.js'></script>
<script src='//ajax.googleapis.com/ajax/libs/jquery/2.1.3/jquery.min.js'></script>
<script src='https://fullcalendar.io/js/fullcalendar-3.3.1/fullcalendar.js'></script>

<div id="c1"></div>
<div id="c2"></div>
<div id="c3"></div>

Answer 1

It's apparently a bug in the library (#3645).