title: R drops hours, minutes, and seconds from date
body: <p>While converting a dataframe to <code>xts</code> I realized that there is something wrong with the formatter. Here's an example dataframe:</p>
  
  <pre><code>effective_date         price
  "1990-01-01"  "100"
  "1990-01-02 00:05:00"  "200"
  </code></pre>
  
  <p>This is example output from a package that I use.</p>
  
  <p>Converting this to <code>xts</code> is straight-forward</p>
  
  <p><code>xts(df["price"], order_by=as.POSIXct(df["effective_date"], format="%Y-%m-%d %H:%M:%S")</code></p>
  
  <p>However this errors out, saying <code>NAs</code> can't be in row names, and the result is:</p>
  
  <pre><code>&lt;NA&gt;       100
  1990-01-02 00:05:00  200
  </code></pre>
  
  <p>Obviously <code>xts</code> can't figure out what to do with the weird date there (midnight) and it won't coerce it. </p>
  
  <p>If I add <code>tz="UTC"</code> to <code>as.POSIXct</code> it doesn't work. Additionally, <code>as.POSIXlt</code> doesnt change anything here either.</p>
  
  <p>What can I do to coerce that midnight date to the correct format?</p>