by Gregg Goldstein Amidst all the chaos and destruction since Russia launched a full-scale invasion of Ukraine, one important part of the picture is often overlooked: some 900,000 exiles who left Russia to avoid prison or being drafted into a war that’s created hundreds of thousands of casualties. A handful of their stories are explored in Patric Chiha’s documentary “ A Russian Winter ” (“Un Hiver Russe”), which has its world premiere Feb. 17 in the Berlin Film Festival ‘s Panorama section.