Unguard two external POST endpoints from CSRF.

src/applications/metamta/controller/sendgridreceive/PhabricatorMetaMTASendGridReceiveController.php

@@ -25,6 +25,9 @@ class PhabricatorMetaMTASendGridReceiveController
 
   public function processRequest() {
 
+    // No CSRF for SendGrid.
+    $unguarded = AphrontWriteGuard::beginScopedUnguardedWrites();
+
     $request = $this->getRequest();
     $user = $request->getUser();
 

src/applications/repository/controller/github-post-receive/PhabricatorRepositoryGitHubPostReceiveController.php

@@ -56,6 +56,9 @@ class PhabricatorRepositoryGitHubPostReceiveController
           "won't do anything!");
     }
 
+    // GitHub POSTs here and doesn't do CSRF.
+    $unguarded = AphrontWriteGuard::beginScopedUnguardedWrites();
+
     $notification = new PhabricatorRepositoryGitHubNotification();
     $notification->setRepositoryPHID($repo->getPHID());
     $notification->setRemoteAddress($_SERVER['REMOTE_ADDR']);