title: Apache 2.4.3 SSI if expr no variables?
body: <p>I have many files with small differences.  The included file contains this, which tries to differentiate on one part of a longer path:</p>
  
  <pre><code>&lt;!--#if expr="${DOCUMENT_URI}=/internet/"--&gt;Internet&lt;!--#else--&gt;Intranet&lt;!--#endif--&gt;
  </code></pre>
  
  <p>In the error log I get</p>
  
  <blockquote>
    <p>AH01337: Could not parse expr "${DOCUMENT_URI}=/internet/" in /opt/apache/htdocs/ssi/time.shtml: Parse error near '$'</p>
  </blockquote>
  
  <p>I find many variations on this theme, like no braces, parentheses around the inside of the quotes, space before the comment end or =~, but nothing helps.  There doesn't seem to be a debug setting for mod_include, which would tell me what's wrong...</p>
  
  <p>Another variant I found is</p>
  
  <pre><code>&lt;!--#if expr='"${DOCUMENT_URI}"=~/internet/'--&gt;
  </code></pre>
  
  <p>this gives no error.  But it always chooses the else branch, likewise with <code>REQUEST_URI</code>, as though the variables were unset.  But I can echo them fine.  I also tried <code>/.+internet.+/</code> in case it was anchoring this.</p>
  
  <p>Since these are CGI variables I also tried loading cgid_module – no good either.</p>