(No Canadian markets report on Dec. 25 due to Christmas holiday) Dec 24 (Reuters) - Canada’s main stock index inched lower at open on Thursday in a shortened trading session, driven by weakness in energy stocks, while hopes for a bigger coronavirus economic relief package in United States limited losses. * At 09:33 a.m. ET (14:33 GMT), the Toronto Stock Exchange’s S&P/TSX composite index was down 4.67 points, or 0.08%, at 17,588.9.