diff --git a/src/applications/differential/storage/DifferentialDiff.php b/src/applications/differential/storage/DifferentialDiff.php
--- a/src/applications/differential/storage/DifferentialDiff.php
+++ b/src/applications/differential/storage/DifferentialDiff.php
@@ -159,6 +159,20 @@
     assert_instances_of($changes, 'ArcanistDiffChange');
 
     $diff = self::initializeNewDiff($actor);
+    return self::buildChangesetsFromRawChanges($diff, $changes);
+  }
+
+  public static function newEphemeralFromRawChanges(array $changes) {
+    assert_instances_of($changes, 'ArcanistDiffChange');
+
+    $diff = id(new DifferentialDiff())->makeEphemeral();
+    return self::buildChangesetsFromRawChanges($diff, $changes);
+  }
+
+  private static function buildChangesetsFromRawChanges(
+    DifferentialDiff $diff,
+    array $changes) {
+
     // There may not be any changes; initialize the changesets list so that
     // we don't throw later when accessing it.
     $diff->attachChangesets(array());
diff --git a/src/applications/diffusion/controller/DiffusionChangeController.php b/src/applications/diffusion/controller/DiffusionChangeController.php
--- a/src/applications/diffusion/controller/DiffusionChangeController.php
+++ b/src/applications/diffusion/controller/DiffusionChangeController.php
@@ -22,8 +22,7 @@
     $drequest->updateSymbolicCommit($data['effectiveCommit']);
 
     $raw_changes = ArcanistDiffChange::newFromConduit($data['changes']);
-    $diff = DifferentialDiff::newFromRawChanges(
-      $viewer,
+    $diff = DifferentialDiff::newEphemeralFromRawChanges(
       $raw_changes);
     $changesets = $diff->getChangesets();
     $changeset = reset($changesets);
diff --git a/src/applications/diffusion/controller/DiffusionDiffController.php b/src/applications/diffusion/controller/DiffusionDiffController.php
--- a/src/applications/diffusion/controller/DiffusionDiffController.php
+++ b/src/applications/diffusion/controller/DiffusionDiffController.php
@@ -54,8 +54,7 @@
       ));
     $drequest->updateSymbolicCommit($data['effectiveCommit']);
     $raw_changes = ArcanistDiffChange::newFromConduit($data['changes']);
-    $diff = DifferentialDiff::newFromRawChanges(
-      $user,
+    $diff = DifferentialDiff::newEphemeralFromRawChanges(
       $raw_changes);
     $changesets = $diff->getChangesets();
     $changeset = reset($changesets);
diff --git a/src/applications/diffusion/data/DiffusionPathChange.php b/src/applications/diffusion/data/DiffusionPathChange.php
--- a/src/applications/diffusion/data/DiffusionPathChange.php
+++ b/src/applications/diffusion/data/DiffusionPathChange.php
@@ -147,7 +147,8 @@
     array $changes) {
     assert_instances_of($changes, 'DiffusionPathChange');
     $arcanist_changes = self::convertToArcanistChanges($changes);
-    $diff = DifferentialDiff::newFromRawChanges($user, $arcanist_changes);
+    $diff = DifferentialDiff::newEphemeralFromRawChanges(
+      $arcanist_changes);
     return $diff->getChangesets();
   }
 
diff --git a/src/applications/diffusion/engine/DiffusionCommitHookEngine.php b/src/applications/diffusion/engine/DiffusionCommitHookEngine.php
--- a/src/applications/diffusion/engine/DiffusionCommitHookEngine.php
+++ b/src/applications/diffusion/engine/DiffusionCommitHookEngine.php
@@ -1115,8 +1115,7 @@
 
     $parser = new ArcanistDiffParser();
     $changes = $parser->parseDiff($raw_diff);
-    $diff = DifferentialDiff::newFromRawChanges(
-      $this->getViewer(),
+    $diff = DifferentialDiff::newEphemeralFromRawChanges(
       $changes);
     return $diff->getChangesets();
   }
diff --git a/src/applications/herald/adapter/HeraldCommitAdapter.php b/src/applications/herald/adapter/HeraldCommitAdapter.php
--- a/src/applications/herald/adapter/HeraldCommitAdapter.php
+++ b/src/applications/herald/adapter/HeraldCommitAdapter.php
@@ -346,8 +346,7 @@
     $parser = new ArcanistDiffParser();
     $changes = $parser->parseDiff($raw);
 
-    $diff = DifferentialDiff::newFromRawChanges(
-      PhabricatorUser::getOmnipotentUser(),
+    $diff = DifferentialDiff::newEphemeralFromRawChanges(
       $changes);
     return $diff;
   }
diff --git a/src/infrastructure/diff/PhabricatorDifferenceEngine.php b/src/infrastructure/diff/PhabricatorDifferenceEngine.php
--- a/src/infrastructure/diff/PhabricatorDifferenceEngine.php
+++ b/src/infrastructure/diff/PhabricatorDifferenceEngine.php
@@ -163,8 +163,7 @@
     $diff = $this->generateRawDiffFromFileContent($old, $new);
 
     $changes = id(new ArcanistDiffParser())->parseDiff($diff);
-    $diff = DifferentialDiff::newFromRawChanges(
-      PhabricatorUser::getOmnipotentUser(),
+    $diff = DifferentialDiff::newEphemeralFromRawChanges(
       $changes);
     return head($diff->getChangesets());
   }