Ignore untracked files in lint repository cache key

Summary: Some people have 2GB+ untracked files in repo which significantly slows down this or even crashes it.

Test Plan: Added a debug output here and linted repo with untracked path.

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin, arudolph

Differential Revision: https://secure.phabricator.com/D4713

src/workflow/ArcanistBaseWorkflow.php

@@ -1549,6 +1549,9 @@ abstract class ArcanistBaseWorkflow extends Phobject {
       $api = $this->getRepositoryAPI();
       $versions = array('' => $api->getSourceControlBaseRevision());
       foreach ($api->getUncommittedStatus() as $path => $mask) {
+        if ($mask & ArcanistRepositoryAPI::FLAG_UNTRACKED) {
+          continue;
+        }
         $versions[$path] = (Filesystem::pathExists($path)
           ? md5_file($path)
           : '');