I am not sure if the new hit to population upon training pioners is suppossed to occur when you begin training, or when training ends....but if I "train pioneer" (by double-clicking on pioneer under training) when I have, say, 100 population, afterwards the city's population still says 100...and it may grow to 110 or whatver by the time the pioneer is actually created - but again, the population stays at 100 (or wahtever) after the pioneer pops out...
