Fixed another embarrassing bug, this time in the SystemClock tests...
Fixed another embarrassing bug, this time in the SystemClock tests...

malcolmr/nodatime,zaccharles/nodatime,jskeet/nodatime,zaccharles/nodatime,jskeet/nodatime,zaccharles/nodatime,BenJenkinson/nodatime,zaccharles/nodatime,nodatime/nodatime,malcolmr/nodatime,nodatime/nodatime,malcolmr/nodatime,zaccharles/nodatime,zaccharles/nodatime,malcolmr/nodatime,BenJenkinson/nodatime