title: tseries: get.hist.quote() gives wrong result
body: <p>According to the following code, the historical quotes of <code>ROG.VX</code> are constant in the chosen time period. However, under <a href="http://finance.yahoo.com/q/hp?s=ROG.VX&amp;a=08&amp;b=09&amp;c=2011&amp;d=02&amp;e=28&amp;f=2012&amp;g=d&amp;z=66&amp;y=132" rel="nofollow noreferrer">http://finance.yahoo.com/q/hp?s=ROG.VX&amp;a=08&amp;b=09&amp;c=2011&amp;d=02&amp;e=28&amp;f=2012&amp;g=d&amp;z=66&amp;y=132</a> one can check that they are not (see the screenshot). What's wrong?</p>
  
  <pre><code>require(tseries)
  hq &lt;- get.hist.quote(instrument="ROG.VX", start="2011-09-09", end="2012-03-28",
                       quote="Close", provider="yahoo", drop=TRUE)
  plot(hq) # =&gt; constant
  stopifnot(hq==138.3) # =&gt; constant 138.3
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/kRGgm.png" alt="enter image description here"></p>