title: How can I update to the end of the current unnamed branch?
body: <p>I <em>thought</em> <code>hg update</code> (with no arguments) would move me to the end* of the current [unnamed] branch, but I believe it will try crossing branches if the other one is newer, which is not what I want to do.</p>
  
  <p>* I'm deliberately avoiding the word "tip" because "tip" refers to the most recent revision, regardless if that named branch has two or more heads.</p>
  
  <p>I'll give some example.</p>
  
  <pre><code>     2       4 (tip)
        o------o
       /
  o---o
       \
        o---o
       1    3
  </code></pre>
  
  <p>I'm at <code>1</code>, but I want to update to <code>3</code> (the end of the branch I'm on). If I type <code>hg update</code> with no arguments it will actually error with the message "abort: crosses branches (merge branches or update --check to force update)". In some scenarios it might even say "abort: not a linear update (merge or update --check to force update)" but I'm not quite sure what triggers that (if you know, please tell me).</p>
  
  <p>If I do <code>hg update --check</code> it will move me to <code>4</code> (the tip of the current named branch), which is not what I want either.</p>
  
  <p>I can check <code>hg log</code> to find out the changeset for <code>3</code> and then <code>hg up 3</code>, but I would like to do it in one command because trying to understand the log is tedious.</p>
  
  <p>Perhaps <a href="http://www.selenic.com/hg/help/revsets" rel="nofollow">revsets</a> could be of use, but I don't know which one would help me.</p>
  
  <p>So, how can I update to the end of the current unnamed branch?</p>