Fix a copy/paste typo with sticky accept

The root issue here is actually just that I cherry-picked stable locally
but did not push it. However, this is a minor issue I also caught while
double-checking things.

Auditors: chad

src/applications/differential/editor/DifferentialTransactionEditor.php

@@ -344,7 +344,7 @@ final class DifferentialTransactionEditor
       $downgrade[] = DifferentialReviewerStatus::STATUS_ACCEPTED;
     }
 
-    if ($downgrade_accepts) {
+    if ($downgrade_rejects) {
       $downgrade[] = DifferentialReviewerStatus::STATUS_REJECTED;
     }