c86f6265d ("relieve the step size limitation..." 2019-02-02)
to 'nostepsizelimit', thus keeping the limit, if not set.
Maximum step size is limited to tstep given by .tran tstep tstop <tstart <tmax>>.
May be overridden by giving 'set nostepsizelimit' to (tstop - tstart)/50.
Both may be overriden by setting tmax.