title: Can't place date strings in data frame that is coming from CSV
body: <p>I am pulling a date with class <code>&lt;chr&gt;</code> format out of a data frame that is loaded from a CSV. 
  I can remove and manipulate it to a date with class <code>&lt;date&gt;</code> and format <code>'YYYY-MM-DD'</code>
  When I go to place it back in the df it turns it to an excel date. </p>
  
  <p>I can pull the excel (class <code>&lt;chr&gt;</code>) out and manipulate into the previous format with <code>as.Date(as.numeric(x), orgin = '1970-01-01')</code> Just can't get it in the df with the correct format.</p>
  
  <p>I tried to create a reproducible example, but this seems only to be the case when loading CSV files. See code below. I think it shows the issues as clear as I can think of without the actual CSV file.  </p>
  
  <pre><code>#pulling it out 
  &gt; l &lt;- CL.Spend[1,]
  &gt; 
  &gt; l
    ï..Apparatus.Contractor.Services..LLC        X      X.1
  4                                       Sep 2018 Oct 2018
         X.2      X.3      X.4      X.5      X.6      X.7
  4 Nov 2018 Dec 2018 Jan 2019 Feb 2019 Mar 2019 Apr 2019
         X.8      X.9     X.10     X.11           X.12
  4 May 2019 Jun 2019 Jul 2019 Aug 2019 Sep 1-18, 2019
  &gt; #manipulating it
  &gt; x &lt;- as.Date(gsub(' ','-01-',l), '%b-%d-%Y')
  &gt; #testing 
  &gt; x
   [1] NA           "2018-09-01" "2018-10-01" "2018-11-01"
   [5] "2018-12-01" "2019-01-01" "2019-02-01" "2019-03-01"
   [9] "2019-04-01" "2019-05-01" "2019-06-01" "2019-07-01"
  [13] "2019-08-01" "0001-09-01"
  &gt; #replacing 
  &gt; CL.Spend[1,] &lt;- x
  &gt; print(CL.Spend[1,])
    ï..Apparatus.Contractor.Services..LLC     X   X.1   X.2
  4                                  &lt;NA&gt; 17775 17805 17836
      X.3   X.4   X.5   X.6   X.7   X.8   X.9  X.10  X.11
  4 17866 17897 17928 17956 17987 18017 18048 18078 18109
       X.12
  4 -718919
  </code></pre>