Exception raised by tbwiki software

Traceback (most recent call last):
  File "/usr/lib/cgi-bin/fuego.cgi", line 55, in 
    main(req)
  File "/home/ubuntu/work/tbwiki/cgi-bin/tbwiki_engine.py", line 2655, in main
    patc = re.compile(".*"+search_string)
  File "/usr/lib/python2.7/re.py", line 194, in compile
    return _compile(pattern, flags)
  File "/usr/lib/python2.7/re.py", line 251, in _compile
    raise error, v # invalid expression
error: multiple repeat