/**
 * Implements hook_menu().
 */
function node_revision_edit_menu() {
  $items['node/%node/revisions/%vid/modify'] = array(
    'title' => 'Modify this revision',
    'load arguments' => array(3),
    'page callback' => 'drupal_get_form',
    'page arguments' => array('node_revision_edit_form', 1, 3),
    'access callback' => '_node_revision_edit_link_access',
    'access arguments' => array('modify revisions'),
    'file' => 'node_revision_edit.admin.inc',
  );
  return $items;
}

function node_revision_edit_form($form, &$form_state, $node, $vid) {

  // Prepare loading the node edit form
  form_load_include($form_state, 'inc', 'node', 'node.pages');

  // Populate the form state.
  $form_state += form_state_defaults();

  // Save the form id for the current content type.
  $nfid = $node->type . '_node_form';

  // Rebuild the entire user edit form for our needs
  $form = drupal_retrieve_form($nfid, $form_state);
  drupal_prepare_form($nfid, $form, $form_state);

  // Setup the already existing log in the field
  $form['revision_information']['log']['#default_value'] = node_revision_list($node)[$vid]->log;

  // Set the "Modify current revision, no moderation" as the default revision operation
  $form['revision_information']['revision_operation']['#default_value'] = 0;

  // Unset the options that we do not need
  // unset($form['options']);

  // Create a new submit button since we do not want to invoke the standard callback functions
  unset($form['#submit']);
  $form['#submit'] = array('node_revision_edit_form_submit');