Added CURLOPT_HTTP09_ALLOWED and --http0.9 for this purpose.
For now, both the tool and library allow HTTP/0.9 by default.
docs/DEPRECATE.md lays out the plan for when to reverse that default: 6
months after the 7.64.0 release. The options are added already now so
that applications/scripts can start using them already now.
Fixes#2873Closes#3383
... like when a HTTP/0.9 response comes back without any headers at all
and just a body this now prevents that body from being sent to the
callback etc.
Adapted test 1144 to verify.
Fixes#973
Assisted-by: Ray Satiro