don't link to bug URLs

Something like this is unnecessary:

    // if we reached here it means there is no active project of this name. Set the cache to express it (See: http://drupal.org/node/421456)
    cache_set('dopl:'. $matches[2], $matches[0]);

You've already explained exactly what that code is doing. There's no need to link to the bug. Your code should not be a historical record; that's what the repository is for ;)

It's sometimes useful to link to a bug report in the project's issue queue -- but rarely. I would say only when the bug is still current and causing a problem or requires a workaround in the module (for instance, it's a bug in another module).