bug/problem with update for merMod

Dear all,

I have an issue with update.merMod function.  
I would like to call it within a function and to send some extra
parameters to it.
The code below fails with an error:

updateModel <- function(model, reml, l)
{

  nfit <- update(object=model, formula.=as.formula(paste(".~."))
                 , REML=reml ,contrasts=l, evaluate=FALSE)
  env <- environment(formula(model))
  nfit <- eval(nfit, envir = env)
  #nfit <- eval.parent(nfit)
  #nfit <- eval(nfit, parent.frame())
}

m <- lmer(Reaction ~ Days +(1|Subject), data=sleepstudy)
updateModel(m, FALSE, "contr.SAS")

Error in model.matrix.default(fixedform, fr, contrasts) : object 'l' not found

eval.parent(nfit) fails as well.