Development record

abcd build next --max 1 on a live series is silently taken as a series move instead of the documented refusal. NextOptions.many() is UntilEmpty || Max > 1, so the count check at nextseries.go (if n.many() && (n.UntilEmpty != st.UntilEmpty || n.Max != st.Max)) never runs for --max 1; a --max 3 series in progress plus 'abcd build next --max 1' continues the series with exit 0, while commands/build.md says a count other than the one the series began with is refused at the pick stage, exit 2. Found by the ruthless reviewer, round 2 of run-2610110908001704 lane-1.