title: Using tilde in ansible "when" statements to build file names from variables
body: <p>The behavior of ~ in ansible "when" statements is puzzling.  For example, if LIB is a fact, set by set_fact, with a value of "lib64" I would expect the following statement to be true if /usr/lib64/cernlib/2006 exists, and false otherwise:</p>
  
  <pre><code>  when: '"/usr/" ~ LIB ~ "/cernlib/2006" is exists'
  </code></pre>
  
  <p>What I find, though, is that the conditional is always true.</p>
  
  <p>The conditional behaves as expected if I omit reference to LIB and just write:</p>
  
  <pre><code>  when: '"/usr/lib64/cernlib/2006" is exists'
  </code></pre>
  
  <p>I can easily imagine a typo that would cause "when" to give me a "false" result, but I'm puzzled by the fact that this always gives me "true".</p>
  
  <p>Am I just doing something wrong?</p>