Detecting BeautifulSoup freeze

[Karthik Venkateswaran]

Parsing the following site using beautifulsoup with html5lib parser hangs but the same works well with html.parser

Site: http://www.webmasterworld.com/google/3584866.htm

#contents is fetched via urllib2
soup = BeautifulSoup(contents, 'html5lib')

soup('a') hangs

but the following works just fine

soup = BeautifulSoup(contents1, 'html.parser')

soup('a')
> [.....]

Is there something wrong with what i am doing or is there a way to detect if soup will fail before making the call to soup('a')

Pastebin reference:
http://paste.ubuntu.com/7125462/

Thanks