[pymtl.tools.sim] add xfail test for issue #128
[pymtl.tools.sim] add xfail test for issue #128

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