title: Hiding .Rproj.user when building packages developed in RStudio
body: <p>A package's <code>.Rbuildignore</code> looks like this:</p>
  
  <pre><code>^.*[.]Rproj.*$
  ^\.Rproj\.user$
  ^.Rhistory$
  [~]
  </code></pre>
  
  <p>Yet <code>R CMD check mypackage --as-cran</code> returns:</p>
  
  <pre><code>* checking for hidden files and directories ... NOTE
  Found the following hidden files and directories:
    .Rproj.user
  </code></pre>
  
  <p>From reading around, it looks like this is a "feature not a bug".  But how do I just prevent <code>.Rproj.user</code> from appearing in the package file in the first place?  Or do I have a problem with my regex?</p>