Does the county have to payoff IRS liens when they foreclose?

I found a property up for Tax Sale next week in Texas. When I spoke to the owner and did my title research there is an additional IRS lien against the property. I was taught that IRS liens trump all other liens/positions but in this case the county has the IRS listed as one of the defendants in addition to the owner of the property! If someone were to buy the property at the tax sale would the IRS lien still be valid? or would it go away b/c they are a defendant in the suit?

IRS jas 130 day ROR.