title: miniCRAN package source downloading
body: <p>I like how it's possible to fix the Rversion with the <a href="http://cran.r-project.org/web/packages/miniCRAN/miniCRAN.pdf" rel="nofollow noreferrer">miniCRAN package's</a> makeRepo function:</p>
  
  <pre><code>makeRepo(pkgs, path, repos = getOption("repos"), type = "source",
           Rversion = R.version, download = TRUE, writePACKAGES = TRUE,
           quiet = FALSE)
  </code></pre>
  
  <p>The documentation says Rversion is ignored if type="source".  Does anyone know why?  Is this a limitation of CRAN in general?  It would be really nice to have this functionality, and I'm not sure of a way around it.</p>