title: Parsing dates with parse_date_time: Why does "2004-04-04 02:00" fail?
body: <p>I am parsing dates with <code>lubridate::parse_date_time</code> and some dates just don't work. For example, why does <code>2004-04-04 02:00</code> return <code>NA</code> but <code>2004-04-04 01:00</code> and <code>2004-04-04 03:00</code> work?</p>
  
  <pre><code>library("lubridate")
  "2004-04-04 01:00" %&gt;% parse_date_time(c("Ymd HM"), tz = "America/New_York")
  "2004-04-04 02:00" %&gt;% parse_date_time(c("Ymd HM"), tz = "America/New_York")
  "2004-04-04 03:00" %&gt;% parse_date_time(c("Ymd HM"), tz = "America/New_York")
  </code></pre>
  
  <p>Here are two other examples that return <code>NA</code>:</p>
  
  <pre><code>"20110313 0240" %&gt;% parse_date_time(c("Ymd HM"), tz = "America/New_York")
  "20130310 0255" %&gt;% parse_date_time(c("Ymd HM"), tz = "America/New_York")
  </code></pre>
  
  <p>I am using lubridate version 1.6.0.</p>