Revision 1806583

On the 'shelve' branch: Keep a backup when deleting a patch.

* subversion/svn/svn.c
  (svn_cl__cmd_table): Mention the backup in the help text.

* subversion/libsvn_client/shelve.c
  (svn_client_shelf_delete_patch): Keep a backup, removing any previous
    backup.
  (svn_client_shelves_list): Ignore backups.