All the signs suggest that one of the longest-serving members of the Rangers squad is entering his final few months at Ibrox. But while a summer departure looks inevitable – some reports claiming that personal terms have already been agreed – there could still be a few potholes in the road. A change of rules, after all, may require a change of stance, and a change of tack. As the Turkish publication Sporx point out, it is far from a foregone conclusion, at this stage, that Borna Barisic will be a Trabzonspor player come the summer, even with his Rangers’ contract expiring on July 1. Borna Bari…