The ruling I referred to is Rev. Rul. 73-329. I wouldn’t say “the IRS is using” this ruling, as I’m not aware of any instance in which the IRS has relied on it. I don’t believe there is any ruling or reg that supersedes it. The problem with the ruling is that it is contrary to the plain language in the law, which applies the wash sale rule in cases where stock is acquired “by purchase or by an exchange on which the entire amount of gain or loss was recognized by law.”
Revenue rulings are nothing more than statements of the position of the IRS at the time they were issued. They aren’t binding on taxpayers, and certainly don’t have to be followed in circumstances where they are contrary to the plain language of the law.