[Rd] read.table() fails with https in R 3.6 but not in R 3.5

[Gábor Csárdi]

Hi Tomas,

On Mon, May 13, 2019 at 11:42 AM Tomas Kalibera
<tomas.kalibera using gmail.com> wrote:
[...]
> This is because (from NEWS:)
>
> The default ‘user agent’ has been changed when accessing http://
>        and https:// sites using libcurl.  (A site was found which caused
>        libcurl to infinite-loop with the previous default.)

Which site was this? Maybe it can be fixed on their end?

The current behavior is not really ideal, because the `libcurl/x,y,z`
string is not only a default, but as you mention above, anything that
start with `R (` is replaced with it, so it is basically impossible to
send out a UserAgent that starts with `R (`. This was very surprising
to me, and I had to go to the C source code to see why R does not
respect my `HTTPUserAgent` option. Would it make sense to document
this in `?options`?

Actually, the default that includes R's version number seems more
sensible to me. Maybe we can just add `libcurl/x.y.z` to that to work
around that buggy site? I would be happy to test this and send a
patch, if you could let me know which website it was.

Thanks!
Gabor

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