BERLIN (Reuters) – A German investigation into Russian-Uzbek billionaire businessman Alisher Usmanov, who is accused of money-laundering and tax evasion, has tested diplomatic relations between Germany and Uzbekistan, the Spiegel news magazine reported on Friday. A series of crisis talks have taken place between the countries’ diplomats, according to the report, including the summoning of the German ambassador in Tashkent in late September. This followed searches carried out at properties registered to Usmanov on the shores of the Tegernsee lake in southern Germany on Sept. 21. The following w…