Drupal\Core\Database\Query\Select::range() doesn't correctly implement SelectInterface

The docs of SelectInterface::range() read:

* @param $start
* The first record from the result set to return. If NULL, removes any
* range directives that are set.

The implementation is:

public function range($start = NULL, $length = NULL) {
  $this->range = func_num_args() ? array('start' => $start, 'length' => $length) : array();
  return $this;
}

It appears that the behavior depends on the number of arguments given, not on the value of $start. EntityFieldQuery has a similar range() method and may supply NULL, NULL to Select::range(). In those cases, the query will never return any results.

My suggestion is to not depend on func_num_args() but actually check the value of $start when it is used.

I will supply patches in a couple of minutes. The bug also exists in Drupal 7, the code is still very similar.

I actually recommend that the handling of $start and $length be split, but that is more of a feature request than a bug.