Index Project milestones to accurately reflect milestone membership

Summary: Fixes T12505. `PhabricatorProjectsMembershipIndexEngineExtension->materializeProject()` was incorrectly bailing early for milestone objects, which prevented milestone members from being calculated correctly. This was causing problems where (for example) an Owners package owned by a milestone wasn't being satisfied when a member of the milestone approved a revision.

Test Plan: Invoked migration, observed that a user's milestones correctly showed up when searched for. Also observed that accepting a revision on behalf of a milestone now satisfies Owners rules.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Maniphest Tasks: T12505

Differential Revision: https://secure.phabricator.com/D18033

resources/sql/autopatches/20170526.milestones.php

@@ -0,0 +1,11 @@
+<?php
+
+$table = new PhabricatorProject();
+
+foreach (new LiskMigrationIterator($table) as $project) {
+  PhabricatorSearchWorker::queueDocumentForIndexing(
+    $project->getPHID(),
+    array(
+      'force' => true,
+    ));
+}

src/applications/project/engineextension/PhabricatorProjectsMembershipIndexEngineExtension.php

@@ -34,29 +34,30 @@ final class PhabricatorProjectsMembershipIndexEngineExtension
   }
 
   private function materializeProject(PhabricatorProject $project) {
-    if ($project->isMilestone()) {
-      return;
-    }
-
     $material_type = PhabricatorProjectMaterializedMemberEdgeType::EDGECONST;
     $member_type = PhabricatorProjectProjectHasMemberEdgeType::EDGECONST;
 
     $project_phid = $project->getPHID();
 
-    $descendants = id(new PhabricatorProjectQuery())
-      ->setViewer($this->getViewer())
-      ->withAncestorProjectPHIDs(array($project->getPHID()))
-      ->withIsMilestone(false)
-      ->withHasSubprojects(false)
-      ->execute();
-    $descendant_phids = mpull($descendants, 'getPHID');
-
-    if ($descendant_phids) {
-      $source_phids = $descendant_phids;
-      $has_subprojects = true;
-    } else {
-      $source_phids = array($project->getPHID());
+    if ($project->isMilestone()) {
+      $source_phids = array($project->getParentProjectPHID());
       $has_subprojects = false;
+    } else {
+      $descendants = id(new PhabricatorProjectQuery())
+        ->setViewer($this->getViewer())
+        ->withAncestorProjectPHIDs(array($project->getPHID()))
+        ->withIsMilestone(false)
+        ->withHasSubprojects(false)
+        ->execute();
+      $descendant_phids = mpull($descendants, 'getPHID');
+
+      if ($descendant_phids) {
+        $source_phids = $descendant_phids;
+        $has_subprojects = true;
+      } else {
+        $source_phids = array($project->getPHID());
+        $has_subprojects = false;
+      }
     }
 
     $conn_w = $project->establishConnection('w');