title: Drush complains about missing timezone despite it being set
body: <p>I'm running Drush Make as part of a Cloudbees Jenkins job. It's constantly dumping errors like this:</p>
  
  <blockquote>
    <p>You are <em>required</em> to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected the timezone 'UTC' for now, but please set date.timezone to select your timezone.</p>
  </blockquote>
  
  <p>I don't understand why this is- I explicitly set the timezone in the first build step, as recommended by the Cloudbees documentation:</p>
  
  <pre><code>#!/bin/bash
  mkdir -p /tmp/php
  echo "date.timezone = America/Chicago" &gt; /tmp/php/php.ini
  export PHPRC=/tmp/php
  php -i
  </code></pre>
  
  <p>This outputs the following, which confirms that the timezone is set.</p>
  
  <blockquote>
    <p>date</p>
    
    <p>date/time support => enabled
    "Olson" Timezone Database Version => 0.system
    Timezone Database => internal
    Default timezone => America/Chicago</p>
    
    <p>Directive => Local Value => Master Value
    date.timezone => America/Chicago => America/Chicago</p>
  </blockquote>
  
  <p>So why on earth would PHP still be complaining in the Drush Make step?</p>