diff --git a/src/applications/differential/mail/comment/DifferentialCommentMail.php b/src/applications/differential/mail/comment/DifferentialCommentMail.php
index 2a1bd2cf16..a206a7aab4 100755
--- a/src/applications/differential/mail/comment/DifferentialCommentMail.php
+++ b/src/applications/differential/mail/comment/DifferentialCommentMail.php
@@ -103,9 +103,9 @@ class DifferentialCommentMail extends DifferentialMail {
     $revision = $this->getRevision();
     if ($revision->getStatus() == DifferentialRevisionStatus::COMMITTED) {
       /*
-      
+
       TODO
-      
+
       $rev_ref = $revision->getRevisionRef();
       if ($rev_ref) {
         $body[] = "  Detail URL: ".$rev_ref->getDetailURL();
diff --git a/src/applications/maniphest/controller/transactionsave/ManiphestTransactionSaveController.php b/src/applications/maniphest/controller/transactionsave/ManiphestTransactionSaveController.php
index 7d87e6c031..c4c22c61b8 100644
--- a/src/applications/maniphest/controller/transactionsave/ManiphestTransactionSaveController.php
+++ b/src/applications/maniphest/controller/transactionsave/ManiphestTransactionSaveController.php
@@ -49,6 +49,7 @@ class ManiphestTransactionSaveController extends ManiphestController {
       case ManiphestTransactionType::TYPE_CCS:
         $ccs = $request->getArr('ccs');
         $ccs = array_merge($ccs, $task->getCCPHIDs());
+        $ccs = array_filter($ccs);
         $ccs = array_unique($ccs);
         $transaction->setNewValue($ccs);
         break;
@@ -59,8 +60,31 @@ class ManiphestTransactionSaveController extends ManiphestController {
         throw new Exception('unknown action');
     }
 
+    $transactions = array($transaction);
+
+    switch ($action) {
+      case ManiphestTransactionType::TYPE_OWNER:
+        if ($task->getOwnerPHID() == $transaction->getNewValue()) {
+          // If this is actually no-op, don't generate the side effect.
+          break;
+        }
+        // When a task is reassigned, move the previous owner to CC.
+        $old = $task->getCCPHIDs();
+        $new = array_merge(
+          $old,
+          array($task->getOwnerPHID()));
+        $new = array_unique(array_filter($new));
+        if ($old != $new) {
+          $cc = clone $transaction;
+          $cc->setTransactionType(ManiphestTransactionType::TYPE_CCS);
+          $cc->setNewValue($new);
+          $transactions[] = $cc;
+        }
+        break;
+    }
+
     $editor = new ManiphestTransactionEditor();
-    $editor->applyTransactions($task, array($transaction));
+    $editor->applyTransactions($task, $transactions);
 
     return id(new AphrontRedirectResponse())
       ->setURI('/T'.$task->getID());
diff --git a/src/applications/maniphest/editor/transaction/ManiphestTransactionEditor.php b/src/applications/maniphest/editor/transaction/ManiphestTransactionEditor.php
index ca02201f42..ce49423785 100644
--- a/src/applications/maniphest/editor/transaction/ManiphestTransactionEditor.php
+++ b/src/applications/maniphest/editor/transaction/ManiphestTransactionEditor.php
@@ -25,7 +25,7 @@ class ManiphestTransactionEditor {
     $email_to = array();
     $email_to[] = $task->getOwnerPHID();
 
-    foreach ($transactions as $transaction) {
+    foreach ($transactions as $key => $transaction) {
       $type = $transaction->getTransactionType();
       $new = $transaction->getNewValue();
       $email_to[] = $transaction->getAuthorPHID();
@@ -51,9 +51,17 @@ class ManiphestTransactionEditor {
       }
 
       if (($old !== null) && ($old == $new)) {
-        $transaction->setOldValue(null);
-        $transaction->setNewValue(null);
-        $transaction->setTransactionType(ManiphestTransactionType::TYPE_NONE);
+        if (count($transactions) > 1 && !$transaction->hasComments()) {
+          // If we have at least one other transaction and this one isn't
+          // doing anything and doesn't have any comments, just throw it
+          // away.
+          unset($transactions[$key]);
+          continue;
+        } else {
+          $transaction->setOldValue(null);
+          $transaction->setNewValue(null);
+          $transaction->setTransactionType(ManiphestTransactionType::TYPE_NONE);
+        }
       } else {
         switch ($type) {
           case ManiphestTransactionType::TYPE_NONE: