http: do not use new API

fixes regressions introduced with davix fix backport

Acked-by:
Target: 2.8, 2.7, 2.6
Require-book: no
Require-notes: no
(cherry picked from commit c65f2d7c73ce8ab6125c92b23c5706c36083d294)
Signed-off-by: Tigran Mkrtchyan <tigran.mkrtchyan@desy.de>
Merge pull request #641 from kofemann/fix-http-2.6

http: do not use new API