title: locale.getpreferredencoding() - why does this reset string.letters?
body: <pre><code>&gt;&gt;&gt; import string
  &gt;&gt;&gt; import locale
  &gt;&gt;&gt; string.letters
  'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'
  &gt;&gt;&gt; locale.getpreferredencoding()
  'UTF-8'
  &gt;&gt;&gt; string.letters
  'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz'
  </code></pre>
  
  <p>Any workarounds for this?</p>
  
  <p>Platform: Linux
  Python2.6.7 and Python2.7.3 seem to be affected, Works fine in Python3 (with <code>ascii_letters</code>)</p>