In oil market standoff with Saudi Arabia, weakened rouble helps Russia

LONDON/DUBAI (Reuters) - In Russia's battle for oil market share with Saudi Arabia, a sharp fall in the rouble has handed the Russians one advantage - they can now produce cheaper than the Saudis, according to Reuters calculations.The Russian currency has lost nearly a fifth of its value against the U.S. dollar - the currency of oil - since their talks on coordinated output cuts collapsed on March 6.Brent crude futures have fallen by nearly 50% to about $26 (22.4 pounds) a barrel and that has..