It's a feature, not a bug.
The second hand sweeps round in 58.5 seconds, then pauses at the top, until an electrical impulse sent over the power grid tells all SBB clocks on the grid
to jump to the next minute. This ensures that all the clocks in all the stations stay in sync without having to go round and check them all against each other.
This was in the 40s, before quartz movements and radio time signals and all that. Very practical... and of course now a cherished tradition.
More info here: http://www.husdal.com/2011/03/05/time-is-precious/