Revision 1878855

Make the hot-backup.py script work with Python 3.

* tools/backup/hot-backup.py.in
  Use functools.cmp_to_key() for sorting conversions, and decode the
  output from svnlook.
  
Patch by: Petyovský Petr <petyovsky{_AT_}feec.vutbr.cz>