title: This warning is not being suppressed by warnings=FALSE
body: <p>MWE <code>test.Rmd</code> file:</p>
  
  <pre><code>---
  title: ""
  author: "Alex"
  output: html_document
  runtime: shiny
  ---
  
  ```{r echo = FALSE, warnings=FALSE}
  a &lt;- max()
  ```
  The value of $a$ in the first code chunk is `r a`.
  
  
  ```{r include=FALSE}
  a &lt;- max()
  ```
  The value of $a$ in the second code chunk is `r a`.
  </code></pre>
  
  <p>Produces:</p>
  
  <p><a href="https://i.stack.imgur.com/l0uxL.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/l0uxL.png" alt="warnings not suppressed"></a>        </p>
  
  <p>The first warning is not being suppressed but the second is by <code>include=FALSE</code>. However, <code>warnings=FALSE</code> has worked to suppress other warnings like package namespace clashes.</p>
  
  <p>The packages I have are:</p>
  
  <pre><code>knitr_1.12.3
  rmarkdown_0.9.6
  </code></pre>