Fix test 006433 and resolve issue #119

Currently the override only sets the defined header and appends the host header unless the host header was set from db_test. This is to ensure the requests remain HTTP/1.1 compliant without calling LW2::http_fixup_request.

It is unlikely to cause any reall issues as test 006433 is the only test in db_test that sets a custom header, but it would be prudent to expand the code to cover potential future corner cases where several headers might be required to be set for the request to work.

Cheers,
Eldar