title: Unable to install 'cli' package from GitHub repository using remotes::install_github()
body: <p>I had recently posted a question about a unicode display issue linked <a href="https://stackoverflow.com/questions/59391083/why-does-r-show-me-unicode-symbols-when-loading-librarytidyverse">here</a>. The problem then was the 'cli' package bug in the version cli v2.0.0. This bug had been brought up and has been solved on the master branch on GitHub by the developer. I am trying to install the same using <code>remotes::install_github("r-lib/cli")</code>. RStudio connects to GitHub fine, downloads the package, begins installing it, goes onto the step for building the package and then returns an error. The error message is copied below:</p>
  
  <pre><code>Error: (converted from warning) Setting LC_CTYPE failed, using "C"
  Execution halted
  Error: Failed to install 'cli' from GitHub:
    (converted from warning) installation of package '/var/folders/n0/__v02y5j02sby1w2_39185sh0000gn/T//Rtmp5HnvTL/file865408954cc/cli_2.0.0.9000.tar.gz' had non-zero exit status
  </code></pre>
  
  <p>Session information: 
  R version 3.6.1
  macOS Catalina</p>
  
  <p>Steps taken to solve the problem:
  1.Have tried using the 'devtools' package to do the same; Same error message
  2.Have reinstalled the Xcode developer tools on the system
  3.Tried removing and reinstalling 'cli'. I can install from CRAN with the same bug in it; still cannot install from GitHub repo. </p>
  
  <p>Any thoughts would be appreciated. </p>