It’s not clear what, exactly, the city will do in early April when the 2015 moratorium on taller buildings in many areas of Boulder expires. During a joint study session of the City Council and Planning Board on Tuesday night, the ordinance’s extension did not appear to be a sure thing. Only four of the nine council members supported extending the 2015 policy. Four others said they were unsure. Planning Board members were more strongly in favor, but also not settled as to how a potentially renewed ordinance would look.