hook_l10n_update_projects_alter can't modify drupal core version number.

Problem/Motivation

hook_l10n_update_projects_alter() implementations can modify the project data collected for translation update. However the core release version data is overwritten with the actually installed version number. It is unknown if other core data is overwritten too.

Proposed resolution

To be determined

Original report by inkling

If you put the following code into a module, it will correctly alter the list of projects to include a specific translation version for panopoly_core. The version will be set to 7.x.1.0-rc3 and l10n info will be correctly added. The version for the drupal project will also be correctly altered:

/**
 * Implements hook_l10n_update_projects_alter()
 */
function l10updproblem_l10n_update_projects_alter(&$projects) {

  $l10n_server = l10n_update_default_server();

  $projects['panopoly_core'] = array(
    'name' => 'panopoly_core',
    'project_type' => 'module', 
    'info' => array(
      'version' => '7.x-1.0-rc3', 
      'core' => '7.x',
      'l10n server' => $l10n_server['name'],
      'l10n url' => $l10n_server['server_url'],
      'l10n path' => $l10n_server['update_url'],
    ),
   );

  $projects['drupal']['info']['version'] = '7.17';
  $projects['drupal']['info']['core'] = '7.x';
  $projects['drupal']['info']['l10n server'] = $l10n_server['name'];
  $projects['drupal']['info']['l10n url'] = $l10n_server['server_url'];
  $projects['drupal']['info']['l10n path'] = $l10n_server['update_url'];
}

However, if you now go to Administration » Configuration » Regional and language » Translate interface, go to the Update tab, and hit the "Refresh information" button, you'll see that the translation for the drupal core project set to 7.19, instead of 7.17.

I think the problem lies in l10n_update_build_projects(). These lines of code are about halfway down the function:

      elseif ($name == "drupal" || preg_match("/HEAD/", $data['info']['version'], $matches)) {
        // Pick latest available release.
        $release = array_shift($projects_info[$name]['releases']);

This overrides the version number provided by hook_l10n_update_projects_alter().

I've tried a couple of different ways to fix this, but none of them satisfactory as yet. If I remove the condition $name == "drupal" form the elseif above, I get 7.17 as I want. However, if I now decide to remove specifying drupal's version number in hook_l10n_update_projects_alter (such as in the first code block above), I get 7.15 for version. This is probably not right, and maybe the reason why the original coder put in the elseif to begin with. This may then mean that the elseif is masking a bug in l10n_update_project_list, which l10n_update_build_projects calls to update the project list.