fix($last-updated): use file author time instead of submodule commit time (#1639)

Author: DvdGiessen

lib/prepare/util.js

@@ -78,7 +78,11 @@ exports.encodePath = function (userpath) {
 exports.getGitLastUpdatedTimeStamp = function (filePath) {
   let lastUpdated
   try {
-    lastUpdated = parseInt(spawn.sync('git', ['log', '-1', '--format=%ct', filePath]).stdout.toString('utf-8')) * 1000
+    lastUpdated = parseInt(spawn.sync(
+      'git',
+      ['log', '-1', '--format=%ct', path.basename(filePath)],
+      { cwd: path.dirname(filePath) }
+    ).stdout.toString('utf-8')) * 1000
   } catch (e) { /* do not handle for now */ }
   return lastUpdated
 }