title: 'as.tibble' causes error in tibble 2.0.1 but not 1.4.2
body: <p>I have written a function part of which converts a matrix to a tibble. This works without issues in tibble 1.4.2 but causes an error in 2.0.1.</p>
  
  <p>The code that causes the error is as follows</p>
  
  <pre><code>library(tibble)
  library(magrittr)
  testmerge &lt;- matrix( data = NA, ncol = 6 + 1, nrow =  0) %&gt;%
        as.tibble
  </code></pre>
  
  <p>The Error message is below</p>
  
  <p><a href="https://i.stack.imgur.com/MOnGB.gif" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/MOnGB.gif" alt="enter image description here"></a></p>
  
  <p>I can solve the problem by doing the following</p>
  
  <pre><code>testmerge &lt;- matrix( data = NA, ncol = 6 + 1, nrow =  0) %&gt;%
    as.data.frame() %&gt;%
        as_tibble
  </code></pre>
  
  <p>But this seems a bit long winded.</p>
  
  <p>What is happening that has caused this change? And how can I easily end up with a tibble of just empty columns?</p>