KYIV – Politics and sports are often an incendiary mix, as the controversy now swirling around the Euro 2012 football championship, to be co-hosted by Ukraine and Poland, demonstrates. German Chancellor Angela Merkel, European Commission President José Manuel Barroso, and other European Union leaders have said that they will boycott matches held in Ukraine, owing to the imprisonment of former Prime Minister Yulia Tymoshenko and other opposition figures.