[plab4] fix plab4-net-sim bugs
[plab4] fix plab4-net-sim bugs

jck/pymtl,jck/pymtl,Abhinav117/pymtl,Abhinav117/pymtl,cornell-brg/pymtl,tj93/pymtl,tj93/pymtl,jck/pymtl,cfelton/pymtl,tj93/pymtl,cfelton/pymtl,12yujim/pymtl,12yujim/pymtl,Glyfina-Fernando/pymtl,cornell-brg/pymtl,cfelton/pymtl,Abhinav117/pymtl,cornell-brg/pymtl,Glyfina-Fernando/pymtl,jjffryan/pymtl,12yujim/pymtl,jjffryan/pymtl,Abhinav117/pymtl,Glyfina-Fernando/pymtl,jjffryan/pymtl