title: Named Subpattern backtracking does not work in PCRE
body: <p>Given the following PCRE regex:</p>
  
  <pre><code>(?(DEFINE)(?'pat'a|ab))^(?P&gt;pat)b$
  </code></pre>
  
  <p>I expected that it would match the strings <code>ab</code> and <code>abb</code>. However, it only matches <code>ab</code> (and not <code>abb</code>, see <a href="https://regex101.com/r/F70wge/1" rel="nofollow noreferrer">https://regex101.com/r/F70wge/1</a>). It seems that the backtracker does not go into the named subpattern.</p>
  
  <p>When inlining the pattern as follows:</p>
  
  <pre><code>^(?:a|ab)b$
  </code></pre>
  
  <p>Both strings <code>ab</code> and <code>abb</code> are matched as expected.</p>
  
  <p>Is it possible to change the regex above (with named pattern) in order to make both strings match without inlining the pattern?</p>