Follow-up D349: Unbreak sync-file

Tags: Release-Engineering-Team

Summary:
This wasn't expecting a file argument:
13:57:56 sync-file failed: <AttributeError> 'file' object has no attribute 'startswith'

Test Plan: Run sync-file

Reviewers: thcipriani, Release-Engineering-Team, mmodell

Reviewed By: Release-Engineering-Team, mmodell

Subscribers: jenkins, bd808

Differential Revision: https://phabricator.wikimedia.org/D401