Don't parse separator tabs as part of the filename in Git diffs which affect files with spaces

Summary:
Fixes T5870. When a filename contains spaces, Git will add a "\t" at the end of the "---" and "+++" lines. We currently consume this and think we're reading a file called "blah blah\t".

Instead, parse it out as not part of the filename.

Test Plan: Added failing unit test and made it pass.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T5870

Differential Revision: https://secure.phabricator.com/D10267

src/parser/ArcanistDiffParser.php

@@ -830,6 +830,10 @@ final class ArcanistDiffParser {
       $remainder = '\t.*';
     } else if ($this->isRCS) {
       $remainder = '\s.*';
+    } else if ($this->getIsGit()) {
+      // When filenames contain spaces, Git terminates this line with a tab.
+      // Normally, the tab is not present. If there's a tab, ignore it.
+      $remainder = '(?:\t.*)?';
     }
 
     $ok = preg_match(

src/parser/__tests__/ArcanistDiffParserTestCase.php

@@ -595,6 +595,12 @@ EOTEXT
         $hunks = $change->getHunks();
         $this->assertEqual(1, count($hunks));
         break;
+      case 'git-remove-spaces.gitdiff':
+        $this->assertEqual(1, count($changes));
+
+        $change = array_shift($changes);
+        $this->assertEqual('file with spaces.txt', $change->getOldPath());
+        break;
       default:
         throw new Exception("No test block for diff file {$diff_file}.");
         break;

src/parser/__tests__/diff/git-remove-spaces.gitdiff

@@ -0,0 +1,11 @@
+diff --git a/file with spaces.txt b/file with spaces.txt
+deleted file mode 100644
+index ae9854d..0000000
+--- a/file with spaces.txt	
++++ /dev/null
+@@ -1,5 +0,0 @@
+-duck
+-duck
+-duck
+-duck
+-goose