search_date not parsing date due to certain keywords/number present in text

[dummynov1]

While running the following script i don't get any date returned:

search_dates("11 sent 12-Dec-2014")
output: None

but if the first digit is any number < 9 or >12, would return the correct date "12-Dec-2014"

search_dates("09 sent 12-Dec-2014")
output: [('12-Dec-2014', datetime.datetime(2014, 12, 12, 0, 0))]

search_dates("13 sent 12-Dec-2014")
output: [('12-Dec-2014', datetime.datetime(2014, 12, 12, 0, 0))]

I have tried using "parsers = [parser for parser in default_parsers if parser != 'relative-time']" in search_date, still the same

May i know if this is a bug, or if i'm doing something wrong?