Differential - stop showing the shield for "move away" operations

Summary: The shield is just confusing. In one case it doesn't work, and in the other case it just shows you a copy of the file you can see just below except in red. Fixes T4599, T1211. Note T1211 proposed not showing the "move away" file **at all** but I think removing the shield fixes the source of confusion. The code here is a bit if / else if / else if... heavy but this is logically sound.

Test Plan: made a diff where i moved a file then edited it in the new location. viewed diff, saw confusing shield, dropped caches, applied patch, viewed diff and saw no shield. made a diff where I moved a file and didn't edit in new location and saw similar shield disappearness.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin, epriestley

Maniphest Tasks: T1211, T4599

Differential Revision: https://secure.phabricator.com/D10865

Author: bobtrahan

src/applications/differential/parser/DifferentialChangesetParser.php

@@ -90,6 +90,7 @@ public function getDisableCache() {
   const ATTR_DELETED    = 'attr:deleted';
   const ATTR_UNCHANGED  = 'attr:unchanged';
   const ATTR_WHITELINES = 'attr:white';
+  const ATTR_MOVEAWAY   = 'attr:moveaway';
 
   const LINES_CONTEXT = 8;
 
@@ -438,6 +439,10 @@ public function isWhitespaceOnly() {
     return idx($this->specialAttributes, self::ATTR_WHITELINES, false);
   }
 
+  public function isMoveAway() {
+    return idx($this->specialAttributes, self::ATTR_MOVEAWAY, false);
+  }
+
   private function applyIntraline(&$render, $intra, $corpus) {
 
     foreach ($render as $key => $text) {
@@ -594,19 +599,22 @@ private function process() {
       }
     }
 
+    $moveaway = false;
     $changetype = $this->changeset->getChangeType();
     if ($changetype == DifferentialChangeType::TYPE_MOVE_AWAY) {
       // sometimes we show moved files as unchanged, sometimes deleted,
       // and sometimes inconsistent with what actually happened at the
       // destination of the move. Rather than make a false claim,
       // omit the 'not changed' notice if this is the source of a move
       $unchanged = false;
+      $moveaway = true;
     }
 
     $this->setSpecialAttributes(array(
       self::ATTR_UNCHANGED  => $unchanged,
       self::ATTR_DELETED    => $hunk_parser->getIsDeleted(),
       self::ATTR_WHITELINES => !$hunk_parser->getHasTextChanges(),
+      self::ATTR_MOVEAWAY   => $moveaway,
     ));
 
     $hunk_parser->generateIntraLineDiffs();
@@ -775,6 +783,8 @@ public function render(
         $shield = $renderer->renderShield(
           pht('The contents of this file were not changed.'),
           $type);
+      } else if ($this->isMoveAway()) {
+        $shield = null;
       } else if ($this->isWhitespaceOnly()) {
         $shield = $renderer->renderShield(
           pht('This file was changed only by adding or removing whitespace.'),