Index reduction issue in Buildings

[casella]

Please check ​Buildings.Examples.ChillerPlant.DataCenterRenewables. The backend fails with

[/var/lib/jenkins/ws/OpenModelicaLibraryTestingWork/OpenModelica/OMCompiler/Compiler/BackEnd/Differentiate.mo:265:5-265:157:writable]
Error: Derivative of expression "bat.P = if con.multiSwitch1.firstActiveIndex == 0 then con.multiSwitch1.y_default else con.multiSwitch1.expr[con.multiSwitch1.firstActiveIndex]"
w.r.t. "time" is non-existent.

I'm not sure why the backend tries to differentiate that expression. Dymola and JModelica compile the model without any problem.