When updating existing accounts, user profile data lost from fields not included in import

To replicate problem: prepare import from CSV, use a CSV file that contains user email addresses for some accounts that already exist, set import settings for profile data to 'replace', perform import.
Expected behavior: the contents of the fields in the CSV file are copied to the respective accounts
Actual behavior: the contents of the fields in the CSV file are copied to the respective accounts, but all other profile data is lost. So if we have profile fields X, Y and Z and import just field X, then fields Y and Z are emptied.

Solution, in /supported/profile.inc, the following code change is necessary:

  foreach ($profile_fields as $field) {
    profile_user_import_save_profile($field, $account->uid, $fields['profile'][$field->fid][0], $updated, $update_setting_per_module['profile'], $data);
  }

should become

  foreach ($profile_fields as $field) {
    if($fields['profile'][$field->fid])
      profile_user_import_save_profile($field, $account->uid, $fields['profile'][$field->fid][0], $updated, $update_setting_per_module['profile'], $data);
  }

I've tested this solution and it works.