title: character(0) warnings when running devtools::load_all(".") in RStudio
body: <p>I have an R package that I've been building in RStudio, let's called it <code>my_pkg</code>. When I run <code>devtools::load_all(".")</code> within RStudio (specifically using the <code>Ctrl + Shift + L</code> shortcut), I get the following message:</p>
  
  <pre><code>Loading my_pkg
  Warning messages:
  1: character(0) 
  2: character(0) 
  3: character(0) 
  4: character(0) 
  5: character(0)
  </code></pre>
  
  <p>All of the functions in the package work fine. My <code>NAMESPACE</code> and <code>DESCRIPTION</code> files are complete with no syntax errors. When I run <code>?my_pkg</code>, however, the help file does not match the specifications provided in the <code>DESCRIPTION</code> file. When I remove the <code>Imports</code> from <code>DESCRIPTION</code>, there is no more <code>character(0)</code> warning message. Of course, I need those imports. When I change <code>Imports</code> to <code>Suggests</code>, there is <code>character(0)</code> warning message.</p>
  
  <p>Here is the description file content, with some stuff changed to protect IP.</p>
  
  <pre><code>Package: scoutdroid
  Title: This is where the title is.
  Version: 0.1
  Authors@R: "Ben Hanowell &lt;benjamin.hanowell@redfin.com&gt; [aut, cre]"
  Description: This is where the description is.
  Depends:
      R (&gt;= 3.1.0)
  Imports:
      dplyr,
      lubridate,
      mboost,
      randomForestSRC,
      RODBC,
      stringr
  License: file LICENSE
  LazyData: true
  </code></pre>
  
  <p>And here is <code>NAMESPACE</code>.</p>
  
  <pre><code># Generated by roxygen2 (4.0.1): do not edit by hand
  
  import(RODBC)
  import(dplyr)
  import(lubridate)
  import(mboost)
  import(parallel)
  import(randomForestSRC)
  import(stringr)
  </code></pre>
  
  <p>When I use the RStudio Build &amp; Reload button in the Build tab, I get the following warnings:</p>
  
  <p>** preparing package for lazy loading</p>
  
  <pre><code>Warning: replacing previous import by 'lubridate::intersect' when loading 'scoutdroid'
  Warning: replacing previous import by 'lubridate::setdiff' when loading 'scoutdroid'
  Warning: replacing previous import by 'lubridate::union' when loading 'scoutdroid'
  </code></pre>
  
  <p><strong>edit</strong> Added some more details to help folks understand what might be going on.</p>
  
  <p><strong>edit 2</strong> I also added the <code>DESCRIPTION</code> file, although I don't provide the full package, which is proprietary.</p>
  
  <p><strong>edit 3</strong> Added <code>NAMESPACE</code>.</p>
  
  <p><strong>edit 4</strong> Added warnings that occur when using RStudio Build &amp; Reload button in the Build tab.</p>