title: 409 error conflict update, updating pouchDB doc
body: <p>I have a weird conflict with my pouchDB code trying to update a document in my database</p>
  
  <p>code:</p>
  
  <pre><code>this.addToExistingUser = function (docId, key, value) {
          usersDatabaseRemote
                  .get(docId)
                  .then(function (doc) {
                      doc[key] = value;
                      return usersDatabaseRemote.put(doc, docId, doc._rev);
                  })
                  .then(function () {
                      console.log('added field: ' + key + ' to doc ' + docId);
                  })
                  .catch(function (err) {
                      console.log("error from addToExistingUser:");
                      console.log(JSON.stringify(err));
                  });
  
   }
  </code></pre>
  
  <p>where :</p>
  
  <pre><code>.factory('usersDatabaseRemote', [
      'pouchDB',
      function (pouchDB) {
          'use strict';
  
          var usersDatabaseRemote = pouchDB('https://id:pwd@id.cloudant.com/boardl_users');
  
          return usersDatabaseRemote;
      }
  ])
  </code></pre>
  
  <p>leads to : </p>
  
  <pre><code>{"status":409,"name":"conflict","message":"Document update conflict","error":true,"reason":"Document update conflict."}
  </code></pre>
  
  <p>But as you can see from the code I take the revision number <code>rev</code> from the remote document so I don't see why is there a problem with this.</p>
  
  <p>Thanks </p>