TOKYO (Reuters) - Japan Airlines Co (JAL) said on Sunday that a Boeing Co 787 Dreamliner jet undergoing checks in Tokyo following a fuel leak at Boston airport last week had leaked fuel during tests earlier in the day. An open valve on the aircraft caused fuel to leak from a nozzle on the left wing used to remove fuel, a company spokeswoman said. The jet is out of service after spilling about 40 gallons of fuel onto the airport taxiway in Boston due to a separate valve-related problem. ...