mailchimp_lists_user_update needs to test if $edit['roles'] is set (incompatibility w/remember_me module)

If you have logintobaggan and remember me installed, there are situations where mailchimp_lists_user_update will throw errors when the user logs in. There is probably/possibly and issue with remember_me, but it only seems to bork mailchimp.

The error is as follows:

Notice: Undefined index: roles in mailchimp_lists_user_update() (line 306 of /website/docroot/sites/all/modules/mailchimp/modules/mailchimp_lists/mailchimp_lists.module).
Warning: array_diff_key() [function.array-diff-key]: Argument #2 is not an array in mailchimp_lists_user_update() (line 306 of /website/docroot/sites/all/modules/mailchimp/modules/mailchimp_lists/mailchimp_lists.module).

The issue occurs here

/**
 * Implements hook_user_update().
 */
function mailchimp_lists_user_update(&$edit, $account, $category) {
  $removed_roles = array_diff_key($edit['original']->roles, $edit['roles']);
  
  mailchimp_lists_user_sync($account, isset($edit['mail']) ? $edit['mail'] : '', $removed_roles);
}

A quick inspection of $edit reveals that $edit['roles'] is not set. So I would like to add a simple if statement check to make sure it's available.

/**
 * Implements hook_user_update().
 */
function mailchimp_lists_user_update(&$edit, $account, $category) {
  if(isset($edit['roles'])) {
    $removed_roles = array_diff_key($edit['original']->roles, $edit['roles']);

    mailchimp_lists_user_sync($account, isset($edit['mail']) ? $edit['mail'] : '', $removed_roles);
  }
}