President Volodymyr Zelensky on Friday signed into law a bill allowing some Ukrainian convicts to serve in the country’s military in exchange for the possibility of parole at the end of their service, a move that highlights the country’s desperate attempts to replenish its forces after more than two years of war. Parliament passed the bill last week, and political analysts were unsure whether Zelensky would enact it given the sensitivity of the matter.The measure echoes a practice that Russia has widely used to bolster its forces and that Ukraine ridiculed at the beginning of the war. But Ukraine is now ceding territory to advancing Russian forces, and the Ukrainian military urgently needs to increase the number of troops on the more than 600-mile front line if it is to prevent Russia from breaking through its defenses. Ukrainian officials have said the measure could allow up to 20,000 prisoners to be mobilized.