title: Checkpoint update issue in R
body: <p>I ran the following line of code to update my checkpoint for R (ML server version) </p>
  
  <p><code>checkpoint("2019-12-30",checkpointLocation = tempdir()</code></p>
  
  <p>but I got the following error.</p>
  
  <pre><code>  |======================================================================================          |  89%Loading required package: emo
    |============================================================================================    |  95%Loading required package: emo
    |================================================================================================| 100%
  - Discovered 307 packages
  Unable to parse 19 files:
  - R/R-3.5.1/library/MASS/scripts/ch16.R
  - R/R-3.5.1/tests/utf8-regex.R
  - R/win-library/3.4/checkpoint/examples/example_checkpoint.R
  ...
  - R/win-library/3.5/timeSeries/extensionsTests/chicPlots.R
  - R/win-library/3.5/timeSeries/extensionsTests/xtsWrappers.R
  
  Error in gregexpr(makeSearchString(pkg), s) : 
    invalid regular expression 'package:{$|package:{
      {
          name
      }
  }$|package:abind$|package:acepack$|package:AER$|package:agridat$|package:akima$|package:alr3$|package:ape$|
  package:asd$|package:betareg$|package:BHH2$|package:Biobase$|package:boot$|package:brglm$|package:brglm.....|
  package:expm$|package:expsmooth$|package:fastICA$|package:fields$|package:forcats$|package:foreach$|package:foreca
  </code></pre>