I don’t know if this is common or not, but Nivi at Venture Hacks seems to think it is prevalent enough to point out more than once. 

I know most entrepreneurs want to get the financing over quickly to return to product developement, but signing a term sheet with a no shop agreement is likely to send you back a month or more if the VC doesn’t end up funding the company.  I can see the insistence of no shop language in larger M&A deals but see no place for them in early stage rounds. 

I can’t imagine allowing a single VC firm the ability freely perform their due dilligence and expect the entrepreneur to sit on his hands and wait.