Don't send empty testplan in e-mail

Summary: Allowed after D2193.

Test Plan: Disable `differential.require-test-plan-field`, create diff without test plan.

Reviewers: epriestley

Reviewed By: epriestley

CC: aran

Differential Revision: https://secure.phabricator.com/D2252

Author: vrana

src/applications/differential/mail/reviewrequest/DifferentialReviewRequestMail.php

@@ -56,9 +56,11 @@ protected function renderReviewRequestBody() {
         $body[] = null;
       }
 
-      $body[] = 'TEST PLAN';
-      $body[] = $this->formatText($revision->getTestPlan());
-      $body[] = null;
+      if ($revision->getTestPlan() != '') {
+        $body[] = 'TEST PLAN';
+        $body[] = $this->formatText($revision->getTestPlan());
+        $body[] = null;
+      }
     } else {
       if (strlen($this->getComments())) {
         $body[] = $this->formatText($this->getComments());