bug#25061: consider adding %COMPAT to default gnutls priority string

[Ted Zlatanov <tzz@lifelogs.com>]

On Fri, 10 Feb 2017 16:51:39 +0100 Andy Wingo <wingo@igalia.com> wrote: 

AW> I tried checking (had to remember what I was doing to begin with!) and
AW> was not able to reproduce the original problem, and therefore couldn't
AW> test NORMAL:%COMPAT or NORMAL:%DUMBFW :/  Sorry :/

AW> I was trying to just do this:

AW>   ;; uncomment to test original proposed workaround
AW>   ;; (setq gnutls-algorithm-priority "NORMAL:%COMPAT")
AW>   (setq gnutls-log-level 2)
AW>   (url-retrieve "https://mirror.hydra.gnu.org/"
AW>                 #'(lambda (status)
AW>                     (message "success")))

AW> and evaluating that last form a number of times.  Not very scientific :P
AW> I was unable to reproduce the problem though.

Thanks, Andy.

We were just talking with Michael about connection-specific settings;
this is a perfect use case. It will be one of the first things we use
for testing. So that will resolve the need for per-connection
adjustments, and we can focus on just the default value.

Does anyone think we should add %COMPAT or %DUMBFW to the default
priority string? Without definitive proof that it will help, I'm not
sure we should, but I'm open to comments. Either way, we'll document it.

Thanks
Ted