title: R install_github: Error: Failed to install 'unknown package'
body: <p>I'm new to GitHub and I'm stumped. I can't get <code>install_github</code> to work.</p>
  
  <p>I followed the helpful instructions here to set up my account: <a href="https://kbroman.org/github_tutorial/pages/init.html" rel="nofollow noreferrer">https://kbroman.org/github_tutorial/pages/init.html</a>. 
  I have an account and a repo where I store some R ggplot settings: 
  <a href="https://github.com/tgraybam/TorontoPlot" rel="nofollow noreferrer">https://github.com/tgraybam/TorontoPlot</a>.</p>
  
  <p>OK. Now I'd like to install the settings file from my repo into an R project, thus: <code>devtools::install_github('tgraybam/TorontoPlot')</code>. </p>
  
  <p>But executing the command returns an error: </p>
  
  <pre><code>Error: Failed to install 'unknown package' from GitHub: HTTP error
  404. Not Found Did you spell the repo owner (`tgraybam`) and repo name (`TorontoPlot`) correctly? - If spelling is correct, check that you
  have the required permissions to access the repo.
  </code></pre>
  
  <p>I have <code>devtools</code> installed. 
  I am not spelling anything wrong. 
  It is my own repo. 
  I can clone it just fine: </p>
  
  <p><code>git clone https://github.com/tgraybam/TorontoPlot.git</code></p>
  
  <p>I can use <code>install_github</code> with different repos (this works fine: 
  <code>install_github("kbroman/broman")</code>.)</p>
  
  <p>I can authenticate. <code>ssh -T git@github.com</code> returns </p>
  
  <pre><code>Hi tgraybam! You've successfully authenticated, but GitHub does not provide shell access.
  </code></pre>
  
  <p>Just like it is supposed to. </p>
  
  <p>I've Googled up a storm and tried everything I can think of (multiple times in multiple orders). </p>
  
  <p>I'm using a Mac. Here are my system and R details: </p>
  
  <pre><code>platform       x86_64-apple-darwin15.6.0   
  arch           x86_64                      
  os             darwin15.6.0                
  system         x86_64, darwin15.6.0        
  status                                     
  major          3                           
  minor          5.2                         
  year           2018                        
  month          12                          
  day            20                          
  svn rev        75870                       
  language       R                           
  version.string R version 3.5.2 (2018-12-20)
  nickname       Eggshell Igloo         
  </code></pre>
  
  <p>Can anyone out there help? Huge thanks. </p>