title: sqldf missing value where TRUE/FALSE needed
body: <p>In sqldf_0.4-7.1 I get:</p>
  
  <pre><code> Error in if (.allows_extensions(db)) { : 
    missing value where TRUE/FALSE needed 
  </code></pre>
  
  <p>Where is the package that fixes the bug? My error is the same as the one generated by:</p>
  
  <pre><code>sqldf("select * from warpbreaks limit 6")
  </code></pre>
  
  <p>I downloaded sqldf v0.4-7.1 from CRAN but with newer source does not help some 8 hours later.</p>