title: mongodump failure 'locale::facet::_S_create_c_locale name not valid'
body: <p>When I try to create a mongodb dump with</p>
  
  <pre><code>$ mongodump -d mydb
  </code></pre>
  
  <p>it fails</p>
  
  <pre><code>terminate called after throwing an instance of 'std::runtime_error'
    what():  locale::facet::_S_create_c_locale name not valid
  Aborted
  </code></pre>
  
  <p>I have <code>LC_ALL=en_US</code>, Ubuntu 10.0.4, MongoDB 2.4.6
  I suspect something is wrong with my locale, but can't find what exactly it is.</p>