if self.mtime_by_filename.get(filename, 0) != mtime:
md5 = file_utils.get_file_md5(filename)
self.mtime_by_filename[filename] = mtime
self.md5_by_filename[filename] = md5
self.all_md5s.add(md5)
if self.mtime_by_filename.get(filename, 0) != mtime:
md5 = file_utils.get_file_md5(filename)
self.mtime_by_filename[filename] = mtime
self.md5_by_filename[filename] = md5
self.all_md5s.add(md5)