title: How can I get readr to handle quoted NA values?
body: <pre><code>library(readr)
  
  csv &lt;- 'x,y
  "1","N/A"
  "N/A","2"
  '
  
  df &lt;- read_csv(csv, col_types = "ii", na=c("\"N/A\"", "N/A"))
  </code></pre>
  
  <p>Running this yields:</p>
  
  <pre><code>&gt; df &lt;- read_csv(csv, col_types = "ii", na=c("\"N/A\"", "N/A"))
  Warning: 2 parsing failures.
  row col   expected actual
    1   y an integer    N/A
    2   x an integer    N/A
  </code></pre>
  
  <p>Practically, the <code>"N/A"</code> values end up as <code>NA</code>, but is there a more elegant way to handle this? For example, this runs without issues, illustrating the desired behaviour.</p>
  
  <pre><code>csv2 &lt;- 'x,y
  "1",N/A
  N/A,"2"
  '
  
  df2 &lt;- read_csv(csv2, col_types = "ii", na="N/A")  
  </code></pre>