Police create cordon on pitch to separate Old Firm fans As if the ugliness of the 120 minutes wasn't enough - the grisly battle, the hair-on-fire panic, the abysmal lack of anything resembling coherence or even competence - there was the disgrace of the post-match. Celtic had made it through to the Scottish Cup semi-finals after one shot on goal and no shot on target. They had survived their way through the day despite their own awful shortcomings, winning on penalties because Rangers were an abomination in reply. On a day of blocks, misplaced passes, crosses flying out of play, free-kicks wasted, aerial duels, hoofball, head tennis, punts downfield, unending fouls and a chronic lack of accuracy, the last act was Tomas Cvancara beating Jack Butland. Or, at least, we hoped it was the last act. It wasn't, of course. The finale to the day involved a pitch invasion from many, many Celtic supporters at the Broomloan Road end. There were 7,500 of them at Ibrox. A return to the way things were pre-2018. Mistake.…