Failure to write to `rprofile.site` on Windows

[alex-trueman]

needs tries to modify the Rprofile.site file when answering the question: Should needs load itself when it's... needed?. On Windows, this requires administrator permission and results in the following error:

Error: package or namespace load failed for ‘needs’:
 .onLoad failed in loadNamespace() for 'needs', details:
  call: file(file, ifelse(append, "a", "w"))
  error: cannot open the connection
In addition: Warning message:
In file(file, ifelse(append, "a", "w")) :
  cannot open file 'C:/PROGRA~1/R/R-3.5.2/etc/Rprofile.site': Permission denied

I don't know how to work around this except to answer "No" to the question. This then requires manual intervention every time I want to use needs.