title: knitr: getting a parse_all error in R when converting Rmd file into HTML
body: <p>I am getting below Parsing error each time I use Knit Html in R for converting my Rmd files into HTML:</p>
  
  <blockquote>
    <p>Error in parse_all(input, filename, stop_on_error != 2L) :    unused
    argument (stop_on_error != 2) Calls:  ... call_block ->
    block_exec -> in_dir -> evaluate -> parse_all</p>
  </blockquote>
  
  <p>Execution halted</p>
  
  <p>Same result is obtained when using knitr or knitr:knit2html from the  command line. Error did not exist before (I have already used Knit HTML for many .Rmd reports) but appeared when I used knit2html from the cmd for the first time. The compilation is only working where there are no R code chunks in the .Rmd file or when the chunks are empty. I work under windows 7, R version: 3.2.3, R studio version: 0.99.902.  Below is the only R code chunk in the test.Rmd file that I am using for testing:</p>
  
  <pre><code>```{r}
  i &lt;- 0
  i &lt; i + 3
  i
  ```
  </code></pre>