Wrong stream builder for sequencer4

[guillecledou]

It is ok upto sequencer3 but on sequencer4 it appears not to remove all intermediate guarded commands

Program

def seq(in1,in2,in3,in4) = {
  i1<-fifofull(i4) drain(i1,in1) o1<-in1 
  i2<-fifo(i1)     drain(i2,in2) o2<-in2 
  i3<-fifo(i2)     drain(i3,in3) o3<-in3 
  i4<-fifo(i3)     drain(i4,in4) o4<-in4 
  o1 o2 o3 o4
}

seq(i1,i2,i3,i4)

Stream builder