PRISTINA (Reuters) – Kosovo police said two of its patrol cars came under fire early on Friday in the country’s north near its border with Serbia, where ethnic tensions are still simmering more than two decades since a war between ethnic Albanians and Serb forces ended. The police said its officers were ambushed and attacked with a hand grenade and an AK-47 assault rifle while traveling at one of the border crossings, but no one was injured. It said it was a fourth attack in the past three days. A police official told Reuters the police was investigating whether the attack was related to smugg…