Fix loop in QueryIterator when row count is an exact multiple of page size

Summary: Ref T13152. The pager does a bit of magic here and doesn't populate `nextPageID` when it knows it got an exact final page. The logic misfired in this case and sent us back to the start.

Test Plan:
  - Set page size to 1 to guarantee rows were an exact multiple of page size.
  - Ran `rebuild-identities` (I no-op'd the actual logic to make it faster).
  - Before: looped forever.
  - After: clean exit after processing everything.

Reviewers: amckinley

Reviewed By: amckinley

Maniphest Tasks: T13152

Differential Revision: https://secure.phabricator.com/D19479

src/infrastructure/storage/lisk/PhabricatorQueryIterator.php

@@ -29,7 +29,7 @@ final class PhabricatorQueryIterator extends PhutilBufferedIterator {
 
     // If we got less than a full page of results, this was the last set of
     // results. Throw away the pager so we end iteration.
-    if (count($results) < $pager->getPageSize()) {
+    if (!$pager->getHasMoreResults()) {
       $this->pager = null;
     } else {
       $this->pager->setAfterID($pager->getNextPageID());