Toggle revision "shouldBroadcast" correctly when "--draft" is used with prototypes off

Summary:
See PHI573. Ref T13120. Drafts were recently changed so that "draft" and "broadcast" are separate flags, and you can have non-broadcasting revisions in states other than "draft" if builds fail on a draft or you abandon a draft.

However, when draft mode is entered with `arc diff --draft` and you have prototypes off, this flag wasn't being set correctly.

Test Plan: Disabled prototypes, created a revision with `arc diff --draft`, observed that `draft.broadcast` is now correctly `false`.

Reviewers: amckinley

Reviewed By: amckinley

Maniphest Tasks: T13120

Differential Revision: https://secure.phabricator.com/D19360

src/applications/differential/xaction/DifferentialRevisionHoldDraftTransaction.php

@@ -22,7 +22,9 @@ final class DifferentialRevisionHoldDraftTransaction
     // TODO: This can probably be removed once Draft is the universal default.
     if ($this->isNewObject()) {
       if ($object->isNeedsReview()) {
-        $object->setModernRevisionStatus(DifferentialRevisionStatus::DRAFT);
+        $object
+          ->setModernRevisionStatus(DifferentialRevisionStatus::DRAFT)
+          ->setShouldBroadcast(false);
       }
     }
   }