bug#34341: 26.1; url-retrieve-synchronously returns blank buffer

[Robert Pluim]

>>>>> On Tue, 07 May 2019 08:35:00 +0200, Robert Pluim <rpluim@gmail.com> said:

>>>>> On Mon, 06 May 2019 20:16:52 -0400, Noam Postavsky <npostavs@gmail.com> 
>>>>> said:
    Noam> I found this smaller change fixes it also.  Is it simple
    Noam> enough to for emacs-26?  Otherwise, we should set
    Noam> gnutls-algorithm-priority because (as far as I understand)
    Noam> we have a broken TLS1.3 implementation at the momement.

    Robert> If we do decide to disable TLS1.3, which Iʼm not really in
    Robert> favour of, changing the defaults in
    Robert> lisp/net/gnutls.el:gnutls-boot-parameters might be better
    Robert> than setting gnutls-algorithm-priority. Iʼd prefer your
    Robert> gnutls.c patch, although I haven't had a chance to test it
    Robert> yet.

That patch to src/gnutls.c fixes my testcase, which is imap over
TLS1.3 to gmail. Itʼs pretty simple, I think it could go to
emacs-26. Eli?

Robert