Differential - fix "transaction has no effect error" on diff create

Summary: Fixes T6658.

Test Plan: made a diff with no repository and default policy and it worked!

Reviewers: epriestley, chad

Reviewed By: chad

Subscribers: Korvin, epriestley

Maniphest Tasks: T6658

Differential Revision: https://secure.phabricator.com/D10910

src/applications/differential/conduit/DifferentialCreateDiffConduitAPIMethod.php

@@ -172,6 +172,7 @@ final class DifferentialCreateDiffConduitAPIMethod
     id(new DifferentialDiffEditor())
       ->setActor($viewer)
       ->setContentSourceFromConduitRequest($request)
+      ->setContinueOnNoEffect(true)
       ->applyTransactions($diff, $xactions);
 
     $path = '/differential/diff/'.$diff->getID().'/';

src/applications/differential/conduit/DifferentialCreateRawDiffConduitAPIMethod.php

@@ -68,6 +68,7 @@ final class DifferentialCreateRawDiffConduitAPIMethod
     id(new DifferentialDiffEditor())
       ->setActor($viewer)
       ->setContentSourceFromConduitRequest($request)
+      ->setContinueOnNoEffect(true)
       ->setLookupRepository(false) // respect user choice
       ->applyTransactions($diff, $xactions);