I wonder if Corbyn may have played a brilliant game here. He understands that his party has adopted no coherent position on Brexit, attempts to 'topple the government' at their moment of weakness to prove to his contemporaries that he genuinely wants the leadership but is subtly aware that he never really had a chance of winning a motion of no confidence anyway. Thus, he can leave the burden of Brexit on May and her indecisiveness.Or maybe Corbyn genuinely thought he could become PM within weeks and he has no idea what he is doing.