title: Rmarkdown no longer working after 1.0.136 R Studio update
body: <p>I recently updated my R Studio to version 1.0.136 and now have the following error when trying to knit documents:</p>
  
  <p><a href="https://i.stack.imgur.com/PEJOj.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/PEJOj.png" alt="enter image description here"></a></p>
  
  <p>I've run <code>getOptions("repos")</code> and would seem to be set to the appropriate CRAN mirror:</p>
  
  <pre><code>                       CRAN 
  "https://cran.rstudio.com/" 
  attr(,"RStudio")
  [1] TRUE
  </code></pre>
  
  <p>Running <code>devtools::install_github("rstudio/rmarkdown")</code> also does not solve the problem and the same error results.</p>
  
  <p>Any thoughts or more information I can provide?</p>