title: PostgreSQL tsrange: is it correct for lower_inf('(-infinity,today)'::tsrange) to be false?
body: <p>In the course of writing a program that accepts tsrange literals from the user, which are then plugged into various SQL queries, today I was testing some tsranges to see how they are interpreted by PostgreSQL 9.3.5.</p>
  
  <p>This one, in particular, behaves strangely: '(-infinity,today)'::tsrange</p>
  
  <p>The lower_inf function says the lower bound is not infinite (!)</p>
  
  <pre><code>test=&gt; SELECT lower_inf('(-infinity,today)'::tsrange);
   lower_inf
  -----------
   f
  (1 row)
  </code></pre>
  
  <p>Yet PostgreSQL reports that this tsrange contains a timestamp like '1000-01-01 BC' . . .</p>
  
  <pre><code>test=&gt; SELECT '(-infinity,today)'::tsrange @&gt; '1000-01-01 BC'::timestamp;
   ?column? 
  ----------
   t
  (1 row)
  </code></pre>
  
  <p>Can anyone shed light on this?</p>