title: tm_map has parallel::mclapply error in R 3.0.1 on Mac
body: <p>I am using R 3.0.1 on Platform: x86_64-apple-darwin10.8.0 (64-bit)</p>
  
  <p>I am trying to use tm_map from the tm library. But when I execute the this code</p>
  
  <pre><code>library(tm)
  data('crude')
  tm_map(crude, stemDocument)
  </code></pre>
  
  <p>I get this error:</p>
  
  <pre><code>Warning message:
  In parallel::mclapply(x, FUN, ...) :
    all scheduled cores encountered errors in user code
  </code></pre>
  
  <p>Does anyone know a solution for this?</p>