Log Message:
latexmk: update to 455.

From v. 4.54c to 4.55
 Correct bug that $search_path_separator wasn't defined under msys.
 Ensure that all configuration variables do have sensible default
   definitions (which wasn't always the case previously).
 Allow optional timeout in pvc mode after a period of inactivity.
   (See documentation for -pvctimeout option.)
 Compensate for problems caused by time offset between system time on
   system running latexmk and file times on remote file system.
   (It caused wrong behavior when a document uses biber, MiKTeX
   is used, the aux_dir is on a remote file system, and the system
   time on the host of the file system differs from the system time on
   the system running latexmk.)