title: Deleting keys using python-gnupg
body: <p>Here's a quick test-case of my workflow:</p>
  
  <pre><code>from tempfile import gettempdir
  from os import path
  from shutil import rmtree
  
  from gnupg import GPG
  
  gnupghome = path.join(gettempdir(), 'foo')
  gpg = GPG(gnupghome=gnupghome)
  gpg.encoding = 'utf-8'
  
  
  def raise_f(error):
      raise error
  
  
  assert_equal = lambda first, second: first == second or raise_f(
      AssertionError('Expected {first!r} to be {second!r}'.format(
          first=first, second=second)
      )
  )
  
  try:
      assert_equal(len(gpg.list_keys()), 0)
      key = gpg.gen_key(
          gpg.gen_key_input(key_type='RSA', key_length=2048, name_real=u'foo')
      )
      assert gpg.export_keys(key.fingerprint).startswith(
          '-----BEGIN PGP PUBLIC KEY BLOCK-----'
      )
      assert_equal(len(gpg.list_keys()), 1)
      assert_equal(
          gpg.delete_keys(fingerprints=key.fingerprint, secret=True).status, 'ok')
      assert_equal(len(gpg.list_keys()), 0)
  finally:
      rmtree(gnupghome)
  </code></pre>
  
  <p>That final <code>assert_equal(len(gpg.list_keys()), 0)</code> raises an <code>AssertionError</code>.</p>
  
  <p>What am I doing wrong?</p>