[tex-live] pretest -> update texlive 2017

[Bob Tennent]

 >|> The page titled Installing TeX Live over the Internet links
 >|> to that page:
 >|>
 >|>   your best bet is to choose explicitly from the list of CTAN mirrors
 >|>
 >|> with no explanation of how to navigate to a texlive
 >|> repository.
 >|
 >|So would you not agree, Bob, that it is the documentation that is at
 >|fault rather than the links as earlier asserted ?

Yes. But perhaps the relevant script could be made more
robust by testing for a tex-archive path. 

Bob