title: R svyglm na.exclude predict and na padding
body: <p>I'm to use predict with the svlgm function and I'm having trouble getting predict to pad out the resulting vector with NAs as I would expect (and indeed can achieve with a non-survey glm using na.exclude). </p>
  
  <p>Running svyglm with na.exclude gives the following error </p>
  
  <p>Warning message:
  In model.matrix(glm.object) * resid(glm.object, "working") :
    longer object length is not a multiple of shorter object length</p>
  
  <p>Am I asking svyglm/predict to do something I shouldn't, or is this an error with the svyglm package? Is there a way of getting predict to produce a vector padded with NAs from a svyglm object?</p>
  
  <p>Any advice/help greatly appreciated</p>
  
  <pre><code>library(survey)
  y=c(0,0,0,0,0,1,1,1,1,1,0,0,0,0,0,1,1,1,1,1)
  x1=c(1,0,1,1,1,NA,2,2,2,2,1,0,NA,1,0,0,0,2,2,2)
  x2=c(10,21,33,55,40,30,26,84,NA,87,20,21,23,25,NA,60,76,84,71,87)
  x3=runif(20)
  foo=data.frame(y,x1,x2,x3)
  
  m1=glm(y~x1+x2, family=binomial(logit),na.action=na.exclude)
  predict(m1) 
  
  
  svy1 &lt;-
    svydesign(
  ids=~0,
  data = foo,
  weights = ~x3
    )
  
  m2 &lt;- svyglm(y ~ x1+x2, svy1,na.action=na.exclude)
  predict(m2)
  </code></pre>